During the time Uchiha Yoichi stayed by Tsunade's side, he also took care of Nawaki.
But mainly, he looked after Tsunade. Nawaki's strength was too weak, so a steady pace of training was enough for him.
Tsunade still had a lot of room for improvement, and she was already a formidable warrior.
Learning Armament Aura and Observation Aura, mastering Sage Mode, implanting the Wood Release Bloodline to increase Chakra Amount and Recovery Power, this was what Tsunade could achieve to the limit as a ninja.
By then, she would be someone with a massive amount of Chakra, nearly impervious to injury, capable of shattering half a mountain with a punch, and perceiving every move of the enemy during battle.
Except for being a little lacking in speed, she could almost be described as having no drawbacks.
As for Genetic Primordial Energy, it was a cultivation technique allowing a ninja to achieve Six Paths level strength without relying on a Tailed Beast, roughly the equivalent of a Seven Gates user when first reaching planet-level.
Reaching high-level planet strength, you could punch with the power of a Tailed Beast Ball, devastate continents in battle, and nearly live for a millennium.
Uchiha Yoichi had plenty of time—currently training Aura with Tsunade, having only recently acquired it himself; his training time only slightly surpassing Tsunade, and yet he still couldn't manage an Aura Wrap.
Tsunade originally wanted to pass on her Monster Strength to Uchiha Yoichi, feeling uneasy about not reciprocating the help from this Shy Little Ghost.
However, Uchiha Yoichi didn't accept it and told Tsunade that upon her return to Konoha, he would teach her a new power technique.
When acquiring the "Tale of the World" ability, Uchiha Yoichi also brought back the World-Ending Spear Technique, which at its peak could unleash six- to seven-fold force. However, Uchiha Yoichi hadn't yet trained in it, wanting to first strengthen his Genetic Primordial Energy.
If he dedicated himself entirely to training, Uchiha Yoichi's progress would surely soar quickly, but that would mean neglecting his family and other matters, something he found monotonous.
His initial goal upon reaching the Ninja World was immortality, which he had almost achieved, so now it's time to really enjoy life.
However, Tsunade felt Yoichi's refusal of her Monster Strength belittled her Ninjutsu, deciding to mentor and reprimand him as a senior, but before sparring, she set the rule that only Taijutsu could be used, not Sharingan Dojutsu.
For several days, the citizens of this small town in the Land of Tea could feel thunderous rumblings from afar, occasionally followed by earthquakes.
After a while, the villagers couldn't bear it any longer and held a festival to pray to the Gods, hoping the persistent earthquakes would stop.
To the civilians of the Land of Tea, this festival seemed effective; after its celebration, the earthquakes ceased entirely.
This led the local townsfolk to preserve this festival, celebrating it annually in hopes of divine protection.
This month brought significant gains for both Tsunade and Uchiha Yoichi.
Tsunade, already exceptionally adept at Chakra Control, quickly applied Armament Aura once understanding its principles, covering it over her hands.
After over a month, Tsunade could almost cover her whole body in Armament Aura, catching up with Uchiha Yoichi. Next was becoming more adept with Aura, making her body harder when covered while ultimately achieving Aura Wrap.
By then, Tsunade might even try to punch away a Tailed Beast Ball, with no fear of injury.
As for Uchiha Yoichi, his defense had become even more frightening; even without any protection, bullets and Shuriken Kunai couldn't break his skin. This was before using Lightning Armor and Armament Aura.
Across the Ninja World, apart from certain special techniques like the Dead Demon Consuming Seal, nothing could breach Uchiha Yoichi's defense.
Observation Aura wasn't challenging for either, as Tsunade already knew some Perception Ninjutsu and just had to adapt it to a new method, making it constant and finer.
This greatly tested Chakra Control, but for Tsunade and Uchiha Yoichi at this level, their Chakra Control was flawless.
The reason they didn't learn many Ninjutsu was that it was largely unnecessary, possibly only needed once in a decade, mainly for teaching students.
Observation Aura was incredibly helpful, whether detecting enemies or aiding in combat, so Tsunade started from scratch like a student learning a new kind of Nin-Taijutsu.
During training, Tsunade and Uchiha Yoichi primarily used Shadow Clones to instruct Shizune and Nawaki, with Tsunade shyly entrusting Nawaki to Uchiha Yoichi.
Calling Nawaki brother-in-law with blushing cheeks, Tsunade only gently knocked on Nawaki's head but didn't object to the title.
Training together and discussing Ninjutsu, after a day's training, Yoichi would accompany her for a couple of drinks after their bath; despite often taking liberties, Tsunade increasingly enjoyed these days.
The little brother she long mourned had been revived, jumping around expressing his dreams from back then; even after being disciplined to focus on training, he hadn't given up on becoming Hokage.