Yamanaka Tohru hadn't noticed the changes in his Sharingan. He continued attending class while training its genjutsu.
Uchiha Fugaku had also come to see Yamanaka Tohru during this time to guide his genjutsu training. Their relationship had grown much better than before.
Yamanaka Tohru quickly learned all the Sharingan genjutsu in the scroll with Uchiha Fugaku's help.
Afterward, he began learning the Rasenshuriken. There were less than three years until the Hizashi Bridge mission, and Yamanaka Tohru had to reach Kage-level strength within that time if he wanted a chance to save Obito at the bridge.
Unlike Naruto in the original story, Yamanaka Tohru didn't have an enormous amount of Chakra and couldn't make hundreds of Shadow Clones. He created two Shadow Clones: one practiced cutting leaves, while the other practiced slicing through a waterfall. Meanwhile, his real body continued teaching the Medical Ninjas.
With Naruto's experience training the Rasenshuriken in the original story, and Namikaze Minato having already completed the technique, Yamanaka Tohru's training progressed much faster than he'd expected.
After about two weeks, he had successfully developed an incomplete Rasenshuriken. At this stage, it couldn't be thrown, and its explosion would injure him. It was like the version Naruto used against Kakuzu in the original story.
Naruto had added Nature Energy to the Rasenshuriken, using it to stabilize the technique and bring it to completion.
Yamanaka Tohru did the same. After entering Sage Mode, he infused the Rasenshuriken with Senjutsu Chakra containing Nature Energy. He activated his Sharingan and watched the Rasenshuriken's interior gradually stabilize after the Nature Energy was added.
Yamanaka Tohru was so focused on observing the changes in the Rasenshuriken that he didn't notice some of the Nature Energy flowing through his body being absorbed by his Sharingan. Before long, the Sharingan that had absorbed