Evil spirit + joins Muzan + eats people + no system.

(The protagonist is very bad! Very bad! No humanity, please don't mind if you accidentally enter!)

Manami, who depended on his younger brother for survival, joined the Demon Slayer Corps and became the disciple of Yoriichi Tsugukuni, the most powerful member of the Demon Slayer Corps. However, he failed to kill Muzan during an encounter with him, and thus became a sinner of the Demon Slayer Corps. He was expelled from the Demon Slayer Corps along with his master Yoriichi Tsugukuni.

When he met Muzan again, he had two choices: become a demon and make those who hurt him pay the price, or continue to live like garbage.

Wan Mi chose the former.

Since you have expelled me, I will live my life in the most horrible way possible!

If the Demon Slayer Corps can't tolerate me, then I will become an evil demon!