I Wanted to Kill Myself, but Was Forced to Save the World

[An original world setting, a protagonist who is no good guy, a little Cthulhu, a little Kamen Rider, and a tiny bit of Honkai: Star Rail. You can enjoy the story even if you’re unfamiliar with them.] “When greed outweighs reason, people become no different from beasts.” That night, in the midst of a downpour, a black book from the future was delivered into Chen Yi’s hands. Forced to accept a plan to save the world, he embarked on a difficult path toward its salvation. But... “Your plan is no good. Use mine.”