Since the war had not yet escalated to the point where Kage-level combatants were required, Hoshiyomi and the others had not gone to the frontlines. Most of the time, they remained in the rear, responsible for drafting war strategies.
Over the course of Year 42, Hoshiyomi appeared rather unmotivated in official duties. He barely handled frontline affairs and instead spent his days with Minato and a boy named Obito—so much so that even Tsunade would gripe about his irresponsibility after finishing her daily training.
Hoshiyomi only muttered a half-hearted response to her complaints, but in his heart he thought: What I'm doing is actually the real work that determines the future of the shinobi world.
That's right. For this entire year, Hoshiyomi had been busy training Minato—and teaching Obito how to fall in love.
These two "big matters" were, in Hoshiyomi's eyes, of immense importance: one would determine Konoha's future after Tsunade stepped down, and the other would shape the entire shinobi world in years to come. But such things couldn't be explained openly; Hoshiyomi could only keep them to himself.
With Hoshiyomi acting as a "love mentor," Obito's romantic progress had gone surprisingly well. He had already officially started a relationship with Rin.
Though a nine-year-old falling in love might sound childish by later standards, in the precocious world of shinobi it was practically set in stone.
Thanks to Hoshiyomi's intervention, Kakashi had clearly defined the nature of his relationship with Rin. And at this point, the new and improved Obito, shaped by Hoshiyomi's guidance, was ready to shine.
Hoshiyomi's "remodeling" of Obito had been all-encompassing. Obito's strength and even his appearance had undergone major improvements. Not just Rin—even many other girls in their class had started noticing him.
By the time the academy students graduated, Kakashi's team realized something startling: the once loud, boastful dead-last Obito seemed like a completely different person.
He no longer clung obsessively to his odd goggles. He no longer picked childish fights with other boys. More importantly, his strength was growing day by day. From being the class's weakest, he had risen to stand among the very top.
That was when the girls realized there had always been a hidden gem among them: strong, kind, and always willing to help others in need.
So this is who Obito-kun really is... we really misunderstood him before.
Even the girls who once mocked him began to think this way. Naturally, Rin—who had always treated Obito kindly—began to waver as well.
At first, her care for Obito had stemmed partly from sympathy and partly from their compatible personalities. But now… she was genuinely moved.
After being "rejected" (in her own imagination) by Kakashi, Obito had appeared at just the right time—when she needed support most. He made her laugh every day, helped her train in taijutsu, invited her to share lunch, and always put aside whatever he was doing to be there for her.
Most importantly, every gesture struck the perfect balance: never so overbearing as to feel clingy, and never manipulative enough to make her feel guilty.
Over time, the simple-hearted Rin began to feel both reliance on and anxiety about Obito. She had grown used to his presence. But now that so many other girls liked him, and his little "fangirls" chased him every day—would Obito someday fall for someone else?
And just like that… Rin fell for him.
While Hoshiyomi occasionally offered "advice" for Obito's romance, he didn't neglect Minato's training either.
The main focus of Minato's training was, of course, the development and advancement of the Rasengan. Hoshiyomi couldn't use the Flying Thunder God Technique at all, so the only way he could help Minato was with this.
By now, Minato had already mastered the first stage of the Flying Thunder God perfectly, and it wouldn't be long before he developed a method for its second stage.
During this period, Minato also realized a flaw in his combat style—his lack of raw firepower. Though using kunai in combination with the Flying Thunder God was efficient, the actual damage output was somewhat lacking.
Against opponents who strengthened themselves with Earth Release or those clad in armor, kunai often fell short. That was when the development of the Rasengan became especially important. Just as Minato was troubled over this issue, Hoshiyomi appeared on cue like a genie from Aladdin's lamp.
Hoshiyomi directly presented a complete training method for the Rasengan—and even demonstrated a finished Rasengan on the spot, which left Minato's imagination running wild.
"You mean a spiraling chakra sphere that simulates a Tailed Beast Bomb, increasing destructive power, forming a ninjutsu that can be released without hand seals—is this what you're aiming for?"
As he spoke, a fully formed Rasengan condensed in Hoshiyomi's hand. For him, it was nothing difficult; his training in nature transformation and Sage Mode gave him near-perfect control over his chakra. Creating a Rasengan was trivial—he could even form a Rasenshuriken with ease.
Hoshiyomi's casual demonstration left Minato dumbstruck.
"That's it! It's exactly what I envisioned. As expected of you, Sensei—you solved a problem that has troubled me for so long with almost no effort."
Seeing Minato's awe deepen, Hoshiyomi secretly felt quite pleased but didn't forget to keep up the act:
"This technique is indeed convenient—almost comparable to the sword energy I use. But I think it can become even stronger."
As he spoke, Hoshiyomi first unleashed the original Wind Rotation technique he had developed. Under Minato's astonished gaze, the spear-shaped Wind Rotation began to shift. Alarmed, Minato quickly shouted:
"Sensei, stop! Such violent wind-nature chakra—if you force it to compress and change shape, it'll explode—"
Minato was already preparing to use Flying Thunder God to escape, but in the next instant, the Wind Rotation in Hoshiyomi's hand transformed into a Rasenshuriken, spinning violently in the air and producing a buzzing roar.
Hoshiyomi looked innocently at Minato while picking at his ear:
"What was that you said?"
Minato's jaw nearly hit the floor.
"Impossible! To condense such violent chakra into such a stable form—it should have exploded instantly! To achieve this must require an absolutely terrifying level of chakra control. I thought my strength had already come close to yours, Sensei, but now I see how shallow my vision really was… The gap between us is still enormous."
Though somewhat crushed, Minato's own development of the Rasengan proceeded much more smoothly under Hoshiyomi's guidance. With Hoshiyomi providing inspiration and helping him sense stable chakra flow, the Rasengan came together almost effortlessly.
Being a natural genius, Minato mastered the Rasengan in less than three days. At this point, he had already grown extremely close to the version of himself from the original story—the one from his prime.
With Hoshiyomi's help, the timeline had been shortened by a full three years.