Demon Slayer: Breathing Water

Percy had failed.
Gaia was never defeated, and her wrath and power decimated all attempts they made to defeat her.
To awaken the only ones capable of defeating her, and saving his friends, Percy had to sacrifice his life and leave everything he knew behind.
But his story was not finished.
Now in a new world, Percy must arm himself with new techniques to defeat demons in a quest to aid a boy named Tanjiro Kamado in curing his Demonic Sister.