Even Jiraiya couldn't keep his curiosity under control anymore. He wanted to see the true destructive power of that jutsu with his own eyes.
Before long, the three of them reached the center of the blast, and the moment Naruto and Jiraiya saw the crater in front of them, both froze on the spot again.
Naruto could hardly believe that a human being could create a scene like this. In front of the three of them was a massive impact crater more than three hundred feet across.
Even Jiraiya couldn't help drawing in a sharp breath. Not even his own Massive Rasengan could achieve anything on this scale. The gap was enormous.
With a grave expression, Jiraiya said, "Akira, once you mastered this jutsu, your combat power jumped to an entirely new level."
Akira, on the other hand, seemed completely calm. "Naruto could learn this someday too. The condition is that he'd need complete control over the Nine-Tails' power first. The physical strain from this jutsu is extreme, but if he has the Nine-Tails' chakra reinforcing his body, that problem can mostly be ignored."
Once Naruto truly gained control over that chakra, both his physical resilience and his recovery speed would become absurd. At that point, the backlash from the Rasenshuriken would be much less of a problem.
As for why Akira could use it safely, that came down to his chakra control. He had covered his palm in an ultra-dense protective membrane of chakra, completely isolating his hand from the damage.
But the level of control required for that was so demanding that even a future Naruto in Nine-Tails mode might not be able to reproduce it, so Akira had no intention of teaching him that particular trick.
Jiraiya glanced at Naruto and shook his head. "This jutsu definitely isn't suited for him right now. Maybe just like you said, he'll need to truly master the Nine-Tails first. This thing is terrifying. It's the strongest Wind Style jutsu I've ever seen."
In Akira's own view, though, his Lightning Style was still superior to this.
That was why Lightning Style remained his most common combat style, with Water and Fire not far behind.
Naruto, of course, badly wanted to learn it, but seeing the seriousness on Jiraiya's face, he understood that this was beyond him for now, especially with the side effects involved.
For the moment, mastering Rasengan alone was enough.
After returning from the back hills, they all went back to the inn to rest.
Naruto, Jiraiya, and Akira, three men in one room, were packed together as usual.
Tsunade and Shizune, meanwhile, each had rooms of their own.
Early the next morning, Akira used his teleportation jutsu and silently appeared deep in the back mountains behind Tanzaku Town.
He spent most of the day there in solitary training.
Only around noon, when the sun was already high overhead, did Akira wander back to the inn.
He hadn't been back in his room long before Tsunade pushed the door open and came looking for him.
The moment she stepped in, her expression was dark enough to make anyone nervous.
Akira looked up from where he sat at the table reading and asked curiously, "What happened? Who managed to make you that angry?"
Without saying a word, Tsunade strode over, grabbed both his hands, and began checking them back and forth with obvious tension.
Only after confirming there wasn't a scratch on them did she finally let out a breath of relief.
Then, with open irritation, she said, "Jiraiya told me you developed some absurdly powerful forbidden-grade jutsu, and that using it could destroy your hands."
Akira finally understood and laughed. "Jiraiya-sama really should learn how to finish a sentence. I did create a jutsu that can cause serious damage to the body, yes, but that's true for other people, not for me. Since I'm the one who developed it, of course I also worked out how to avoid the risk."
"You just spent all that time checking me over and didn't find anything wrong, did you?"
He had only meant it as a light joke to ease the mood.
Unfortunately, Tsunade was taking this very seriously.
When she forcibly pinned him in place to run a full-body medical inspection, Akira could only smile bitterly and protest, "I was joking. Do you really have to take it this far?"
In the end, she still checked him from head to toe and only finally let the matter go once she confirmed there wasn't even the slightest hidden damage left behind.
"Good. Your body's functioning normally," she said. "But from the way Jiraiya described it, that jutsu can sever the body's internal connections down at the cellular level."
"If that's really the case, then no matter how advanced the medical ninjutsu is, and no matter how strong someone's regeneration is, it wouldn't be enough to save them."
She fixed him with a hard stare.
"What exactly is going on inside your head? How do you come up with a jutsu like that?"
Akira shrugged and smiled. "It's basically just an upgraded Rasengan. Rasengan is the peak of shape transformation, right? So I just added some extra nature transformation into it, and this is what came out."
"I'll admit, the power is ridiculous. Still, it's not as natural for me as Lightning Style."
That was the truth. Compared with the flashy Rasenshuriken, Akira still preferred the direct brutality of Lightning, Fire, or Water jutsus.
To him, Rasenshuriken was more of an experimental result, something born out of curiosity.
The same was true of Raikiri. He'd already developed that too, but had kept it stored away without using it.
At this point, Akira's approach to creating and learning jutsu was driven almost entirely by interest.
And because of that, he had accumulated a frightening number of high-level A-rank and S-rank jutsus without even noticing.
Tsunade looked at him with unusual seriousness. "A jutsu like that is the kind of trump card you do not reveal casually again. The moment a ninja's true cards are fully exposed, they're already halfway to the grave. Even with people close to you, you don't show everything."
Akira's smile faded, and he nodded properly. "I understand."
Tsunade's warning really was valuable advice. Once a ninja's abilities became common knowledge, it became far easier to target them in an assassination.
That was how figures like the Third Kazekage and the Fourth Kazekage ended up dead.
If those men had been facing enemies head-on in a fair fight, someone like Sasori would never have stood a chance against the so-called strongest Kazekage in history.
But assassination was a different game entirely.
In this brutal ninja world, once someone understood your weaknesses and held the right information, even a jonin killing a Kage-level enemy wasn't unheard of.
Of course, if you were in the category of Madara Uchiha or Hashirama Senju, then most of those dirty tricks stopped mattering.
Those two were beyond the ordinary scale of shinobi altogether.
That was also why the leaders of the great villages rarely left home unless absolutely necessary. Too many people were always looking for the chance to strike.
The ninja world never lacked hidden monsters.
So Akira appreciated Tsunade's concern more than he let on.
Once that heavy subject was over, he looked at her and said, "Good timing. There are a few medical ninjutsu problems I wanted to ask you about."
He then summarized the difficulties he'd run into while reading and laid out several key issues that had been giving him real trouble.
His interest in medical ninjutsu was genuine.
He studied it simply because he liked it.
When Tsunade saw the problems he raised, even she frowned. They weren't simple questions.
Some of them were issues she herself had run into in earlier research, and not all of them had perfect answers yet.
So the two of them shut the door, stayed in the room, and argued back and forth over the material for several hours. In the end, putting their heads together, they finally broke through each one.
After the last issue was resolved, Tsunade let out a slow breath and said, "If I hadn't talked this through with you today, I'm not sure I would've untangled all of those on my own. Akira, at this point, your grasp of medical ninjutsu may already be the closest in the entire ninja world to mine."
Akira closed the book and answered modestly, "I'm still far behind you. But medical ninjutsu really is fascinating. The deeper I dig, the more I realize how much more there is."
With serious matters settled, the two of them drifted into idle conversation.
These days, though, Tsunade rarely spoke about her past anymore.
Maybe she didn't feel there was any need.
Maybe she didn't want Akira carrying unnecessary discomfort in his heart.
The two of them had established a different kind of understanding now, and if she kept bringing up Dan Kato all the time, then no matter how broad-minded Akira was, it would still leave a knot somewhere.
So ever since Tsunade had truly accepted Akira's place beside her, she had stopped speaking Dan's name, and even mention of Nawaki had become rare.
Truthfully, Akira didn't care that much either way. Tsunade had loved other people before. That couldn't be changed, and there was no point pretending otherwise.
As long as the person she chose now was him, that was enough. Obsessing over the past was exhausting.
If Tsunade had truly been unable to let go of what came before, Akira would've stepped back cleanly.
Without resentment.
That would've been her freedom.
At the same time, Akira not wanting to stand beside someone whose heart was somewhere else—that was his freedom too.
Fortunately, both of them seemed to understand that without ever needing to say it outright.
From the moment Tsunade had first taken his hand, some things had already become obvious. Akira did have a streak of possessive pride in him, but he also had the strength and the presence to match it.
Power, looks, and a personality that was easy to get along with.
Even if he came from a civilian background, plenty of exceptional women in the shinobi world wouldn't care much about that.
Tsunade understood very well that she couldn't keep acting like the same rough, careless woman she had always been and expect that to work forever around him.
And she certainly wasn't stupid enough to stand in front of someone important to her now and keep publicly mourning someone from before.
Straightforward didn't mean foolish.
Around noon, Tsunade suddenly looked at him and said, "Why don't you sign a summoning contract with Katsuyu too? If you had Katsuyu assisting your medical ninjutsu, your results would improve again."
A huge part of why Tsunade's medical ninjutsu stood at the top of the world was because of Katsuyu's support.
Tsunade had a famous nickname in the ninja world for exactly that reason.
Even her longtime rival Chiyo had often called her "that slug woman," because so many of Tsunade's most powerful support methods depended on Katsuyu.
Akira thought for a moment, then answered honestly, "I don't really need it. I never planned to use medical ninjutsu as my life's work."
"I study it purely because I enjoy it."
After hearing that, Tsunade fixed him with a completely unyielding stare.
The two of them locked eyes for several seconds.
In the end, Akira was the one who gave up first. He let out a helpless laugh. "All right, all right. Fine. I'll do it. Having one more summon doesn't exactly hurt me."
The second he agreed, Tsunade smiled at once and immediately pulled out the summoning scroll she had clearly prepared in advance.
"Good. Come on, sign here."
Seeing how ready she'd been, Akira found it hard not to laugh. It wasn't as if he'd been about to run away.
With a quick sweep of the brush, he wrote his name.
Then he bit his finger and pressed a blood-mark over it.
In that instant, Akira felt a strange, distinct connection form between himself and Katsuyu of Shikkotsu Forest.
He formed hand seals and called out, "Summoning Jutsu!"
Poof!
A puff of white smoke rose and faded, and a miniature Katsuyu appeared atop the table in front of him.
The moment she materialized, she greeted them in that soft, gentle voice of hers.
"Akira-sama. Tsunade-hime."
Tsunade braced both hands on the table and smiled at Katsuyu. "Akira is your contractor now too. Take good care of him."
Katsuyu nodded obediently. "Yes. Understood."
After a short exchange, Akira released the summoning and sent Katsuyu back.
Then he looked at Tsunade and joked, "So does this make me the first shinobi in the world to hold contracts with two of the three great sage lands at once?"
Tsunade nodded, then naturally slipped closer and hooked herself around his arm with an amused smile. "It does. Most people don't have luck like yours."
The sudden softness against his arm nearly made Akira stop breathing for a moment. He drew in a slow breath and said honestly, "Your existence really does feel a little unfair sometimes."
Tsunade rested her head lightly against his shoulder and smiled, not missing the meaning behind the complaint. "Oh? And that bothers you?"
Akira wisely chose not to answer aloud.
Inwardly, though, he was thinking that if Tsunade didn't have such overwhelming presence, maybe things never would've developed this far in the first place.
Just as his thoughts were beginning to wander in a direction he absolutely should not let them go, he sensed Jiraiya approaching.
He immediately straightened up, returned to a perfectly composed posture, and said quietly, "Jiraiya-sama's coming."
Tsunade reacted just as fast. Her face warmed a little, and she quickly adjusted her expression and posture, slipping right back into the earlier atmosphere.
By the time she leaned against the table again, it looked as though she was simply continuing to explain a difficult point of medical ninjutsu to him.
Less than a minute later, Jiraiya shoved open the sliding door.
Seeing Tsunade in the middle of an entirely proper academic discussion with Akira, he paused in visible surprise.
Then he grinned and teased, "Well, well. Tsunade, you're actually taking this seriously now. You're really teaching."
With that, he flopped down across from them and poured himself a cup of tea.
Jiraiya, with all the subtlety of a battering ram, noticed absolutely nothing strange in the atmosphere between the two of them.
Akira had spent six or seven years hiding his true abilities already. By now, his control over his expressions was near flawless.
Tsunade, meanwhile, had over fifty years of experience behind her. That showed up in a lot more than appearance.
Hearing Jiraiya's teasing, she shot him an annoyed look. "Akira has real talent for medicine, so naturally I'm teaching him more. Unlike you, who spends all day being a shameless old degenerate."
Jiraiya had heard versions of that insult so many times his ears were probably numb. He didn't care in the slightest and just laughed as usual.
Still, watching him like this, Akira did feel the slightest trace of guilt.
He knew perfectly well that Jiraiya had spent decades carrying feelings for Tsunade and getting nowhere.
And now Akira had stepped into the middle of that.
Which, looked at one way, really was a little unfair.
Then again, after thinking about it for half a second, Akira told himself that his preferences really were obvious.
He liked women who were beautiful, mature, and carried real force in both personality and presence.
There was one additional non-negotiable condition too: they had to be strong.
Anko Mitarashi and Yugao Uzuki, for example, were both attractive, but in terms of actual strength they simply didn't measure up.
And weakness in the shinobi world meant risk.
Akira couldn't spend every moment playing guardian to someone who couldn't protect herself.
That was why he'd always kept those people as friends, nothing more.
As for Hinata and Ino, those two were like girls from the neighborhood he'd watched grow up, and both of them were tied to major clan politics behind the scenes.
Akira appreciated them well enough, but he had never been able to see them in that way.
Maybe they were too familiar.
Maybe they simply weren't there yet.
At the end of the day, they were still kids.
And Sakura? That was Sasuke's whole problem. Akira had no interest in stepping into that mess.
No matter how he looked at it, ever since things with Tsunade had changed, everyone else had abruptly become much less interesting.
Jiraiya, sitting across from them, did have the faintest sense that the two of them might have grown unusually close.
But then he saw them calmly discussing medical theory and immediately dismissed the thought as ridiculous.
Tsunade was over fifty.
Akira was Naruto's age.
How could a thirteen-year-old boy possibly be interested in a woman old enough to be in her grandmother years?
Sure, Tsunade looked young because of her jutsus, but her actual age wasn't exactly a secret.
They were over thirty years apart. The gap between them was deeper than the Mariana Trench. There was simply no way anything genuinely bizarre could be happening there.
Jiraiya shook his head and decided he'd clearly spent too much time in certain places lately. His brain had gone bad.
Watching the two of them talking and smiling, he said, "We head back tomorrow. You should both get your things together."
Akira and Tsunade both looked up at him at the same time.
Akira answered casually, "What's there to prepare? We check out and leave."
Tsunade said nothing, but nodded in agreement.
Seeing the identical response from both of them, Jiraiya's mouth twitched. "All right, all right. My mistake for asking."
Something about the two of them still felt strange to him.
He just couldn't put his finger on exactly what.
As they resumed talking as though no one else existed in the room, Jiraiya abruptly felt extremely unnecessary just sitting there.
Meanwhile, Naruto was still suffering in the back hills, grinding away at his training.
Shizune, for her part, had shown remarkable restraint over the last several days and kept her distance whenever Tsunade went to see Akira.
And so, the three of them passed one more night in that atmosphere, strange and harmonious at the same time.
After one final day of rest in Tanzaku Town, they finally packed up and prepared to leave.
Stepping through the town gate, Tsunade stretched broadly and rolled her shoulders with a smile. "Finally. We're out of this place."
Jiraiya laughed and said, "Really? You looked pretty happy here to me. This is the most famous gambling town in the whole ninja world. Shouldn't it have been your paradise?"