"Yo! Morning, Ren!"
On the main street of Konoha, a blonde boy and a red-haired girl walked side by side. The boy was currently waving at a black-haired youth not far ahead of them.
The three were of similar age, all members of the same graduating class from the Ninja Academy and newly minted Genin as of this year.
"Minato, Kushina. Out on another date?" Ren Kurogane turned around and teased the familiar duo.
Being teased by an acquaintance was too much for the thin-skinned Kushina. Her face instantly flushed a brilliant beet-red as she stammered out a clumsy defense. "Who—who's on a date with this guy?! We just happened to run into each other after heading out!"
Ren simply chuckled, choosing not to poke a hole in her story. He looked at them and asked, "No missions for you two today either?"
Minato nodded, his tone tinged with a hint of helplessness. "Yeah. Jiraiya-sensei was sent to the front lines. For the foreseeable future, our team only exists in name."
Though only ten years old, Minato was precocious. He understood in his heart that once a war began, it was difficult to end. At the very least, it wouldn't be over within a few years.
Consequently, he never counted on Jiraiya to personally supervise his growth. If he wanted to become stronger, he had to rely on his own efforts, and...
Minato's gaze fell upon his friend, Ren. Ren's strength was already above his own; moreover, Ren had researched a remarkably powerful ninjutsu and was currently developing others. Their destructive potential was immense, not falling short of the previously developed Rasengan.
That's right. My name is Ren Kurogane, a traveler. I arrived in this world known as Naruto a year ago and became Minato's classmate.
In that year, relying on his adult soul, Ren had cultivated a good relationship with Minato, effectively securing a connection with the future Fourth Hokage. He had even played matchmaker for Minato and Kushina ahead of time. The two were already in a relationship, though Kushina was still too shy to admit it when asked.
Naturally, as a traveler, a "Golden Finger" was an essential accessory. Ren had his own: a mysterious space that allowed him to communicate with versions of himself from other worlds.
When he first crossed over a year ago, Ren encountered another version of himself in that mysterious space—one who had reincarnated into the world of One Piece. That version was of noble birth and already possessed formidable strength. With a simple fist-bump in that space, their powers synchronized. Ren didn't just gain the powerful physical constitution of his One Piece counterpart; he also inherited the cultivated Haki and all the associated combat memories.
Upon leaving the space, his strength had skyrocketed, landing him squarely at the level of a Konoha Jonin. Furthermore, because his physical energy had increased so drastically, his chakra reserves were incredibly abundant. His current chakra volume was roughly three times that of Minato's.
One shouldn't assume Minato's chakra reserves were small; anyone capable of becoming Hokage would never have a shortage of chakra. For Ren to have three times that amount was a testament to how terrifying his reserves truly were. High-level ninjutsu like the Rasengan were child's play for him.
Speaking of which, while attempting to develop the Chidori a few weeks ago, he had demonstrated the Rasengan in front of Minato. Minato had taken an immediate liking to the move and learned it from him. Ren wondered how his progress was coming along.
Back then, Ren had only taught Minato the first and second stages of the training. If Minato had mastered those, he would be ready for the third.
"Hehe! Ren, come to Training Ground 7 this afternoon!" Minato gave him a pointed look, his voice full of excitement.
Ren immediately understood what he was planning. He didn't refuse, nodding as he accepted the invitation.
The group split up shortly after. Minato and Kushina continued their date, while Ren had his own matters to attend to.
Over the last few days, aside from training, Ren had been considering his future path.
It had been some time since graduation, and Ren had realized his teammates were mostly there to make up the numbers. Such teammates might very well give up being ninjas and return to farming after experiencing their first real life-and-death struggle.
Thus, his teammates were unreliable. As for his sensei, while a Jonin, Ren's Haki perception told him the man was as ordinary as a Jonin could get—his actual strength was inferior to Ren's own.
The only thing the man could offer was experience; beyond that, he was of no help to Ren's growth.
"The One Piece version of me hasn't appeared in a long time. I wonder what's happening on his end?"
Since that brief meeting a year ago, Ren hadn't seen his counterpart again. He was beginning to worry if that version of himself had kicked the bucket...
Because everyone had been in their respective worlds for different lengths of time, they were bound to be influenced by their environments despite starting as the same person. Over time, differences were inevitable.
For instance, Ninja Ren had only recently arrived and was still quite cautious, whereas Pirate Ren had been there for years. He had long since lost his initial wariness, becoming somewhat boisterous as his power grew.
Returning to his small house, Ren methodically organized his belongings. After lunch, he set out for the designated meeting spot.
When he arrived, Minato was already there.
"Minato!" Ren chirped, jumping down beside him. "Finished the training?"
"After two weeks of practice, I've finally completed the mastery of this technique!"
Seeing the jubilant Minato, Ren stepped aside and pointed to a wooden post behind him. "Try it out on the post. Let's see the power."
Without hesitation, a sphere of violent, blue chakra instantly manifested in Minato's palm. He slammed the "ball" directly into the wood!
Boom!
With a sharp blast, the wooden post was struck by the high-speed rotating chakra, leaving behind a jagged, vortex-shaped crater. Minato nodded in satisfaction and looked toward Ren, awaiting his evaluation.
"Not bad. That counts as completing the second stage of the Rasengan," Ren said with a nod. Noticing Minato's confused look, Ren gathered a Rasengan in his own hand and pressed it gently against the post.
Vroom—vroom—vroom!
The blue sphere in Ren's palm didn't simply explode and vanish upon contact like Minato's. Instead, it acted like a meat grinder, completely pulverizing the section of the post it touched into sawdust that scattered across the ground.
Even after the Rasengan had bored completely through the wooden post, the sphere in Ren's hand remained perfectly intact!
"What?!" Minato was stunned. He had suspected before that what he and Ren were practicing might not be the same thing. Now, it seemed his suspicions were correct.
"Ren! How did you keep it from bursting?"
"It's not actually that hard. You just have to maintain the chakra within your palm!" Ren smiled and pulled a balloon from his pocket. He blew it up, tied it off, and handed it to Minato. "The final stage of training officially begins now!"
...?!
Minato looked at Ren with a face full of question marks, not understanding why he was being handed another balloon.
"The third stage of training is this: maintain the results of the first two stages within this tiny balloon!"