Chapter 49: Eureka

For once, it was Tsunade that was trying to bury herself into Riku’s chest and not the other way around. She was happy as hell and just wanted to melt into her son. Cuddling with him did her a lot of good the previous evening when she came back home. She had had to deal with the fall out of the impromptu Kyuubi’s attack and that tired her to no end.

As expected some people blamed Naruto for it but her staunch denial, Minato’s appearance and their explanation of what happened and why had calmed most of everyone down. The revelation that Naruto was the son of their greatest hero had finally broken down the villager’s irrational hatred for him for the most part. He still has been a pranking little shit in his youth and the people still remember that despite not having made a single prank since he graduated and became a genin.

When the villagers lauded Minato for defeating the Kyubi again, he categorically denied any involvement with that. One of the shinobi that had been present on the wall, shouted that it had been Riku who had done it and Tsunade confirmed that it was indeed her son who did the deed. Minato didn’t hesitate to reveal his relation to the dirty blonde too. And an explanation about how that could be possible was given. That had been the second slap on the face for the villagers who realized their mistake towards the “son of a traitor”.

Lots of guilt had been going around but Tsunade declared that today and tomorrow would be a day of celebration for Konoha emerging victorious against another challenge that life sent at them. Everyone got behind the idea immediately and the mood in the village did a total 180.

Because the event had been very public, the subject of Karin becoming the Kyubi’s second host had been talked about. Again, reassurances were given and Karin was presented as a hero by the three kages for willingly sealing the fox inside herself to protect the village.

That night, Riku’s, Naruto’s and Karin’s names were heard all around the village  when toasts were made. Hiruzen was glad to see that his village was finally returning back to what it used to be and what it should be. Without hatred.

“Mom, we need to get up.”

“Noooo.” she whined trying to bury herself deeper into his chest.

“Come on, it’s late and I’m sure everyone has-”

“RIKU!”

The door to Tsunade’s bedroom burst open and one familiar redheaded kunoichi made her entrance. On the spot Karin used her chain to separate Tsunade from her boyfriend while tying up the said boyfriend. The commotion had gathered every inhabitant in the manor just outside the door to witness the tongue lashing of the century.

“You’re ballsy! To leave your hospital bed and the village without saying a word of goodbye to me! However you seemed to be under the delusion that there wouldn’t be any repercussions for that!” she began yelling.

“K-karin-chan.”

“Don’t Karin-chan me! You’re a bastard, ya know?!”

She was so furious that her hair separated in nine different locks and began to defy gravity by going up. She even lost control of her verbal tic.

““Holy crap!””

Both Minato and Naruto were familiar with what was happening because of Kushina doing the same when she was really angry. They knew Riku was in very deep shit. For her part the older redhead had a grin on her face, proud that apparently it was now a thing but more importantly, proud that Karin had a verbal tic. A proper Uzumaki in her opinion.

“What?! You two idiots have something to say? Then say it if you do, ya know?!”

Karin was on a roll. She had switched targets from Riku to Naruto and Minato who quickly ran away to save their lives. Kushina simply began to laugh and followed them at a leisure pace.

“And my happy, peaceful morning is ruined.” Tsunade said with a sigh and ordered Karin to release Riku. “Lovers quarrel later, breakfast first.”

Giving him one nasty look, the redhead let her boyfriend go and he immediately swept her into his embrace.

“What ar-”

He gave her one hell of a kiss while molesting one of her buttocks and melted away her anger. Soon enough she had one leg behind his own ass and she was pushing him towards her.

“I said breakfast first!” shouted the Hokage who hit her son and probably her soon-to-be daughter in law on the head. She then separated them and dragged them out to the living room where three additional faces were present. One belonged to Hiruzen. Two belonged to Ino and Hinata. The latter was relieved more than anything to see Riku healthy and the former was relieved too but also very very angry. Ino proved it right when she rose from her seat, slapped the shit out of Riku then grabbed his collar and pulled him down for a very intense kiss.

“You better not disappear on us again like that! Got it?” Ino’s voice was colder than the Land of Snow.

“Yes, Ino, I promise.”

“Wait, I thought you two broke up?!” Naruto exclaimed dumbfounded.

“Why would you think that?” Ino replied flatly.

“Because he’s with Karin-chan?!”

“He’s also with Hinata, so your point is?”

“Say what?!”

“Hm… We’re all in a relationship with each other, Naruto-kun.” revealed Hinata and if Riku didn’t know any better he would have swore there had been a bit of vindictiveness in her voice.

“B-but.. That’s not… That’s not how it’s supposed to work!” the orange clad blond pointed out.

“We don’t care.” the bluenette simply replied and brought Riku to sit next to her. “We’re happy and that’s all that matters.”

To the side, Hiruzen was amused and a bit envious. So was Minato but he liked to live so said nothing in the presence of his wife. He did mentally high-five his son though. Kushina was frowning but said nothing, it wasn’t her business and while she didn’t approve, she was open to the possibility of love really being shared between the four.

Shizune came in with breakfast and Riku, by force of habit, helped her set everything up. After eating the most important meal of the day and cleaning up they began to talk about how Riku healed.

“Well… I theorized that through the use of nature energy it may be possible for me to regrow my missing limbs. So I-”

“Hold on! Missing limbs?” interjected Minato.

“With the exception of my right arm I lost every appendage while on a mission to save Jiraiya’s ass from his own stupidity.”

“I’m pretty sure such healing is impossible from nature energy. I should know I’m a toad sage myself.”

“Yet here I am. There is also the possibility of my chakra being special, I’m an 8th Uzumaki after all but I don’t think it played much in my healing process. I just channeled nature energy in combination to my medical chakra to slowly regrow everything. Eyes included. It’s like… Hm… Like a plant regrowing itself, I suppose. My cells simply didn’t divide, they knew how to divide themselves in a way that would regenerate my limbs. Which is another point confirming there is more to a cell than what the world currently knows, mom. As if the whole body’s blueprint was stored in every single cell.” he finished by looking at Tsunade.

“We’ll look into that.”

“One thing I wonder is how come you didn’t have any slug physical change?” Kushina asked. “Minato’s eyes become like those of a toad.”

“I think that’s because you learned senjutsu with the toads the toad way.” he replied looking at the Yondaime. “While I did learn under Katsuyu-chan she let me find my own way and offered me no help beyond some advice. As such I wasn’t influenced by her physically. The toads use their special oil, don’t they? I think that’s why you get toad traits when entering sage mode.”

“Hashirama-sama didn’t have any animal trait when he channeled nature energy. He had markings yes, and his eyes changed color to yellow but nothing else.” shared Hiruzen.

“Hold on! Why wouldn’t Katsuyu help you? She adores you to hell and back!” pondered Tsunade.

“Because she’s not my personal summon. She’s yours. And should you undergo senjutsu training she will help you with more than just advice. You should by the way. I think it’s possible to not only alter your cells' degenerescence but also reverse it. You could technically live forever or be young forever.”

“Why didn’t she tell me that?!”

Quickly, Tsuande rose from her seat and went to the patio to summon Katsuyu and have a few words with her. No one who knew the blond was surprised by how vain she showed herself to be.

“But isn’t it the same principle as your Boobie Expansion Jutsu?” Karin wondered aloud to everyone’s confusion.

“The what jutsu now?!” exclaimed an outraged but secretly very interested Kushina.

“That… was the name I gave to an experimental jutsu that… well… Grew mom’s breasts the first time I hit her with it. It’s now called Iryoken. Basically by hitting someone with my medical chakra I can rejuvenate the cells and push them to divide at a very fast pace. When I hit mom, I gave a second puberty to her chest. I was thirteen and suffering from a concussion, okay?!” Riku quickly defended himself under Kushina’s less than impressed gaze.

“And it works wonders now.” Karin pushed him deeper in the shit by grabbing her boobs from under them and lifting them up to show them to Kushina.

“Technically I can do that for any part of the body. It’s a long and very meticulous process.”

“Can you do my butt?”

“Ino, it’s perfect.” Hinata replied. “You don’t need to change it.”

The conversation drifted off from there and everyone did his own thing. Hiruzen, with his curiosity satiated, left the manor. So did Hinata and Ino who had things to do. Karin stayed and talked with Kushina about being a jinchuriki and seals. Minato took Naruto outside for training and invited Riku who agreed since he didn’t have anything better to do.

Naruto began to make a dozen shadow clones and all of them began to make a rasengan.

“What is he trying to do?” Riku asked from the side, looking at his half-brother.

“We’re trying to add his wind nature to the rasengan.” answered Minato, who was watching Naruto attentively.

“The rasengan? Looks to me like that thing the Kyuubi did.”

“It is because I got the idea from that attack. It’s called a bijudama by the way.”

“So… from what I can see… You compress chakra into some kind of vortex into the shape of a sphere?”

“That’s pretty much it. The flow of chakra must go in all directions but at the same time fast enough to have any effect.”

“Why is it so big?”

“Pardon?” Minato was confused.

“The sphere, why is it so big? Isn’t the whole point of the jutsu to compress a maximum of chakra into the smallest sphere possible to maximize its explosive power when the sphere breaks? Naruto is wasting a lot of chakra in my opinion with the way he does it now and underpowering it.”

Minato looked at his eldest son with an open mouth. He was shocked. It was the point of the rasengan but he believed he was done with the jutsu when he created it. The fact that he didn’t work on it further and just made it bigger by pumping more chakra into it, made the whole jutsu pointless. Minato had succeeded in creating a very powerful jutsu but completely went against the very principle it had been created on when he used it.

“That’s… True.” he admitted.

“It’s difficult to make in the first place, ya know?!” Naruto said as he approached them to hear what they were talking about. “I had to use a clone to help me shape it at first. My chakra control was that bad.”

“With how big your chakra reserves are, it’s no wonder. Wait! Did you say you used another clone to make it?”

“Yeah! I needed more hands to shape the sphere.”

“Then why aren’t you using a clone to help you put your wind nature into it?”

Both Naruto and Minato’s jaws dropped at the simple idea.

“You guys really need to begin thinking with shadow clones in mind. Now let’s see this rasengan.”

Riku held his palm face up and started to gather chakra in it and spinned it. He got a flat disk at first then tried to move the chakra to make a sphere. His first result was a vertical disk but quickly understanding how it worked bit by bit the chakra took the proper shape. He heard Minato whistle indicating he was impressed.

“That’s really hard. I have the chakra control but I’m not used to manipulating it that way.”

“You’ll get it with practice.” Naruto said.

“Now, let’s try compressing it further.”

Concentrating on the task at hand, bit by bit the sphere began to shrink to the size of a marble.

“Okay, that was easier than making it in the first place. Hard but easier. Now I just have to think of a way to throw it and-”

““Throw?””

“Well, yes. I don’t want to be near that when it detonates. Didn’t the Kyubi shot its version?”

“That’s a valid point. I guess the rasengan is far from being a complete jutsu, more than just adding nature affinity in it.” Minato conceded.

“Hmm…” Naruto looked closer at the marble and using a finger, flicked it away with strength. The rasengan flew with speed from Riku’s palm and hit a tree that immediately disappeared in an explosion of chakra and so did his friends in a ten feet radius. The three blondes looked at the damage done in silence, completely dumbfounded.

“Somehow… I don’t think that, out of the five nature, adding wind to the rasengan would be good for ourselves if we don’t find a way to use it from a distance.”

“Yes.”

“Shadow clones it is.” replied Minato and Naruto respectively.

Training resumed for his brother while Riku decided he had done enough ninjutsu for the day. He told the others he was going back in to research some fuinjutsu and Minato actually followed him, interested in that. They found Kushina and Karin talking about seals and joined them. Quickly it turned into a teaching class with Riku as the instructor.

“So basically if you want to do something related to space-time you better use a barrier to make things simpler by limiting the space you want to affect. Especially for Time.” Minato said, tapping gently the top of his pen onto his lips.

“Yeah.” replied Riku absentmindedly doodling in his notebook.

“Wait. If a barrier creates a new closed space disconnected from the outside then it’s possible to manipulate the space inside of it in whatever way we want, no?”

Rilu took his book of seals and tossed it to his step-mother.

“Page 33. Better unsealed it on the patio’s ground.”

Raising a brow in curiosity, Kushina rose from her chair and did as instructed. When the Botib came into view, Minato got curious too and joined his wife. She just opened the closet and gasped in shock when he got to her.

“HOLY…”

“You expanded a subspace?!” exclaimed his father.

“Yeah. A few years ago.”

“But how?!”

“The wood, Minato! Look!” Kushina pointed out very thin black lines going through the wood of the closet, both inside and outside. Getting close to take a better look and by squinting his eyes, the former Hokage saw tiny little lines of seals that couldn’t have been done by hand.

“I’m… stumped. Clearly the walls outside and inside of the closet are lined up with seals but I don’t understand how you could write them so small.”

“That’s a very good question. Let me give you a hint: the seals I wrote were no smaller than this one.” Riku said and showed them a healing tag from the table. It was a bit bigger than a regular handwriting size.

Both parents began to think for a while. Minato’s mind went to the seal themselves shrinking by the effect of another seal while Kushina went in the other direction.

“It’s not the seals that changed size, at least not directly, it’s the wood?”

“HumHm. Go on.”

“You… expanded the wood somehow, wrote the seal on them, then returned the wood to its normal size and the seals shrunk with it in some blurry lines. It is the opposite of a tattoo deforming when the skin expands.”

“Correct. I needed more room for bigger seals that I wanted to put in my book. The only way I could think of was to expand the paper then shrink it back. And since paper is made out of wood, it worked for it too. In the case of the Botib, I expand the inside of the wood and carve more seals to maintain the expansion.”

“How big is it inside?” asked Minato.

“Hmm… There is an infirmary for four beds, a bedroom for six beds. A bathroom, a kitchen, a training room as big as the main room that you see now then the main room. In theory as long as the chakra is in enough quantity it’s possible to make that space infinite. Now that I know of nature energy I’m going to incorporate a draining seal that would use nature chakra in the environment to power everything.”

“Anbu must have a field day with this.”

“They do. The Anbu commander has been trying for years to get the Sandaime then mom to authorize the creation of an Anbu affiliated only R&D seal division with me as its head. Instead they just get what I can make in my spare time.”

“At least once a month we treat her at the hospital for trying to drink herself to death because Tsunade-sama keeps refusing her request.” enlightened Karin with a chuckle.

“Can we get a tour?”

Riku nodded to Kushina’s request and showed them the inside of Botib. It didn’t take long, ten minutes at best, before they returned to the main room to take a look at the weapon corner.

“Why is it called Botib?” the redhead asked.

“It stands for Bigger on the Inside Box.”

“That’s so lame!”

“I told him!” Karin’s voice came from outside. “He didn’t want to hear anything!”

“Well, I personally think it’s a good name.” Minato said.

“Of course you would, Mister “Halo Frozen Dessert Hair Whorl Jiraiya Twin Formula Sphere.”

“The what now?” Riku wondered, confused.

“The rasengan’s name before I named it the rasengan.” replied Kushina.

“... Shit, did I get the bad naming sense?”

Kushina snorted and Minato let out a dry embarrassed chuckle. Riku let them study the Botib on their own by telling them the do and don’t about it. Most notably to not destroy the walls or touch the time seal in the middle of the room. He gave a heartfelt kiss to Karin and left to visit his teammates. Kakashi, as usual, was difficult to track down so Riku went to see Yugao instead. He was in luck as she was home. When she opened the door and saw him, she took him in her arms for a nice hug.

“I’m glad to see you alright. The last time, you were bleeding from everywhere and almost dead.” she said.

They retreated inside and Yugao made some tea that she served him.

“I got lucky by having good teammates. And by the toad that was still there to catch me during my fall and reverse summoned to Jiraiya. I’m glad to see you too. Mom, told me Team Yukari was disbanded with me out of commission, soooo what did you do?”

“Kakashi reformed Team 7 with his students. For my part I… took missions here and there with Anko and Kurenai or Izumo and Kotetsu. Though I’ve been wondering for a while about becoming a jonin-sensei.”

“Not returning to Anbu, then?”

“No, that part of my life is over for good.”

“That’s reassuring. You’d make a good jonin-sensei with your no-nonsense attitude. Your students would get their naivety beat out of them.”

“True.” she replied with an amused smile.

They talked further about what happened in the village during his months of absence but also in the Elemental Nations as a whole. From what she heard here and there Iwa lost both of his jinchuriki and Kumo one of them. Akatsuki was getting busy and the two members they captured had disappeared from inside their own cells. Nobody found out how and it was worrying. Both the MP and T&I were pulling out their hair because of it. That gave Riku an idea and the vacant look in his eyes he had when that happened was not missed by Yugao who knew him well.

“Go.” was all she said.

“Hm?”

“You have an idea in mind. Don’t deny it, I know you do. I know that look you have. I also know that you won’t focus on anything else until you deal with that idea, so go.”

Riku nodded, finished his tea and stood up. He gave her a loving kiss on her cheek and quickly left her apartment after thanking her for her hospitality. Quickly he made his way to the Hokage Tower to speak with his mother. Hiruzen and the elders were also present and were talking about the ramification of Minato and Kushina’s news of being alive, and how it would play with Iwa and Kumo. When she saw Riku coming into her office, Tsunade recognized the look on his face and immediately dismissed the Anbu and activated the privacy seals.

“I haven’t said anything yet.” Riku said a bit disturbed by his mother's action.

“I know you. Now what kind of S-rank secret are you going to blurt out?”

“I heard about the disappearance of the two Akatsuki members who were into our custody.”

“You know what happened?”

“Not exactly but the odds are high that space-time ninjutsu was involved.”

“Ninjutsu? Not Fuinjutsu?” asked Hiruzen.

“It’s possible but I doubt it. The knowledge required to pull that off with a seal is… Someone would need to be at least on Minato’s level. No, my idea was to, one: incorporate the Hiraishin into Konoha’s barrier, that way it would be possible to act very fast. Two: to actually put a special hiraishin seal onto each prisoner and put an anchor in their cells. They escape? The barrier corps activates the seal and the escapee are locked back again in a more secure cell. All ready for T&I to ask questions about how they broke out in the first place.”

“Hm. The second option is actually a very good idea. The first would necessitate tempering with the village barrier and so far only Lady Mito knew anything about it.” Homura said.

“Not surprising, she made it.” Koharu commented.

“Speaking of Hiraishin, I thought you couldn’t use it offensively, yet you did yesterday.” His mother noted. He picked from his back pouch a shuriken and tossed it at her.

“Wood?”

“I see. You expanded the wood, wrote the whole seal and shrunk it.” said the Sandaime in contemplation.

“That’s quite clever. It may not do any damage at all but that's not the point of it so it doesn’t really matter.” realized Homura.

“Cherry on the cake, since the chakra needed for the teleportation comes from a central anchor point and not the shurifuin itself, I can safely combine them with the Shuriken Shadow clone Jutsu. Also less expensive and easier to make than Minato’s tri-pronged kunai.”

“Make the seals for the prisoners and you can have a look, just a look at the barrier.”

“I’m on it! Be done by the end of the week.” Riku replied as he left.

“You know… Maybe testing children at the academy for an affinity with fuinjutsu wouldn’t be a bad idea.” thought aloud Hiruzen.

“Sensei, Riku is a genius.”

“You can’t expect to find a fuinjutsu prodigy in each class, Hiruzen.”

“There is merit to the idea. Obviously we can’t expect another seal master but maybe more shinobis inclined to the art? With how many seals Riku and Karin are coming up with, they can’t do everything alone, even with shadow clones. Kushina could help of course but she’s another seal mistress. Do we really want them to spend their time on mundane seals when they could do research for more important ones?” Homura suggested.

“Hm… No, we cannot. Riku has too much on his plate currently. Supplying Anbu and T&I, finishing the Hiraishin completely, finishing to seal the third basement of the hospital… I’m pretty sure I’m forgetting some things. We really need more people dealing with low level seals. Maybe I could ask Minato? Since he can’t be a shinobi anymore he may as well teach the new generation. Both Fuinjutsu and the shinobi arts.”

“That’s an excellent idea, Tsunade.” commented Koharu.

Back with Riku, he quickly made it home and created dozens of Shadow clones to work on the new tasks Tsunade has given him. He retired to his Botib (with the door opened in case someone wanted to talk to him) and picked up his brush.

“Ugh. It’s so debilitating.” A clone grunted putting to the side his twenty second seal.

“Yeah. Why can’t we come up with a clone jutsu that would just clone the seal?” another whined.

“It would be a clone, it wouldn’t last.” said a third.

“What we need is someone else doing this for us. Our life expectancy is way too short and I don’t want to spend it writing seals!”

“Yeah! I’d rather do the dishes or any other chores. At least I would feel useful by seeing something that I accomplish.”

“““Yeah!”””

“I agree guys, except there is no one but us to make the seal and it’s not like it can duplicate itself on its own.”

“...”

All the clones and Riku raised their heads from the seals they were working on and were contemplating this last thought.

“Holy shit! We’re idiots!”

““““Yeah!””””

They all arrived at the same conclusion, the same idea. Thus, all the clones popped themselves knowing they were free of the task at hand while Riku began to cackle so loud that both Kushina and Karin popped their heads through the door.

“Does he do that often?” the older Redhead asked.

“Only when he has a very, very brilliant idea.”

They observed Riku (still cackling) writing furiously with his brush on a huge page made of chakra paper as if he was possessed. In less than five minutes he was done and held the seal he had just made in front of him to examine it.

“KAAAARRRi- Oh, you’re here! And Kushina-san too! Perfect!” he began to yell but saw his girlfriend present at the door and tone it down.

“What do you need?” inquired Karin getting inside the closet.

“Please look at this and tell me what you think.”

She did and so did Kushina. After examining the seal from every angle, Karin put down the page and looked at Riku with wonder in her eyes.

“You made a seal that would make seals!” Kushina exclaimed.

“Yeah! You put a blank tag on the middle part and the pre registered seal in the matrix is applied to the tag! No more slaving away with making seals in large quantities!”

“That poses a problem with chakra supply. There will come a point where chakra will run dry.” Noted Kushina.

“Not if we use the chakra battery seal! More complex would be to create a seal draining and stocking the nature energy on the surrounding. It would be self sufficient!”

Karin grabbed his head and kissed him violently before pulling back.

“You handsome man! You just did away hours of work for me! No more medical tags to do! I can work on my research!”

She pulled him up by his hand and dragged him to the bedroom area. In less than a few minutes, Kushina quickly left the Botib, closing the door behind her.

“Kushi-chan? Is something wrong? Your face is all red.”

Minato had just come inside from the backyard and had caught her fleeing her step-son’s sexual escapade (not that he knew about that). Not saying a word, she used her chain to tie Minato up and dragged him away to their own bedroom.