Creak...
As he pushed open the cyan wooden door, which was already lightly stained with dust, the long-awaited sunlight poured wantonly onto Tobirama's face.
Being in the dim underground for so long made the warm afternoon sun appear somewhat blinding. Tobirama gently raised a hand to shield his brow, and only after fully adapting did he lower his arm and let out a heavy breath of turbid air.
Casually releasing the barrier he had set up, a slightly fatigued Tobirama Senju stepped out of the laboratory where he had spent three whole months.
"Teacher Tobirama, your experiment is finished?!"
At the exit of the underground laboratory, Sarutobi Hiruzen, who was on shift guard duty today, looked pleasantly at Tobirama as he walked over, his gradually maturing face filled with respect.
"Ah, Monkey, you've worked hard."
Tobirama nodded slightly. He was quite satisfied with this disciple of his. After all, following his own older brother, the position of Second Hokage would most likely be handed over to him, and as for the candidate for the Third Hokage after him, he still leaned more toward personally cultivating one himself.
And indeed, he had found a few talented young people to serve as his personal guard unit. Calling them a personal guard unit was actually treating them as half-disciples of his own, because cultivating candidates naturally meant he had to teach them things.
Among his several disciples, Sarutobi Hiruzen was undoubtedly the most outstanding one. Perhaps inheriting the excellent genes of his father, Sarutobi Sasuke, Sarutobi Hiruzen was born with chakra of all attributes, which also meant he could learn all ninjutsu in the entire Shinobi World except for Kekkei Genkai without any threshold.
Coupled with Hiruzen's quite decent comprehension skills, he not only quickly learned the ninjutsu taught to him, but could