Shikkotsu Forest
In this dark, damp world, the most eye-catching sight was an enormous slug that occupied its center like a mountain.
The slug was anxiously watching a pale green pool beside her. The pool itself was far from ordinary.
Although it was not very large, what filled it did not seem to be ordinary water.
The pale green liquid looked thick and dangerous, constantly bubbling as though anyone who carelessly entered it would be dissolved without leaving even a bone behind.
At that moment, the Slug Sage was closely watching a figure in the pool.
Indeed, a naked, muscular figure was submerged in that dangerous pool. If he had not occasionally moved, he could easily have been mistaken for a corpse.
That figure was Shin Uchiha.
Shin Uchiha sat cross-legged at the bottom of the pool, his brow furrowed, as streams of natural energy invisible to the naked eye poured endlessly into his body.
His body was like a bottomless pit, taking in every bit of that natural energy.
Of course, this came at a price. The liquid in the pool was the medium he used to train in Sage Mode-the Slug Sage's saliva.
Although her saliva helped Shin Uchiha absorb natural energy quickly, it was extremely corrosive. Training in Sage Mode with it not only caused intense pain, but a single careless mistake could leave him dissolved without a trace.
Even Tsunade, one of the Sannin, could not master Shikkotsu Forest's Sage Mode despite her Senju Clan bloodline and the rapid healing provided by her Yin Seal.
Only Hashirama Senju and Shin Uchiha, who possessed a Sage Body, could withstand its fiercely corrosive effects on their flesh and continue training in Sage Mode.
Of course, possessing a Sage Body only ensured that they would not be corroded to