Eminence In Shadow Manga !free! -

Most isekai protagonists want to be the hero or the villain. Cid Kagenou wants to be the guy who looks like a background character but secretly possesses god-like power. In his previous life on Earth, he trained tirelessly in martial arts and mental discipline, only to realize that no amount of human training could stop a nuclear bomb. After dying in a freak accident involving a truck (the classic isekai catalyst), he is reincarnated into a world of magic.

The manga is a parody of isekai and power-fantasy tropes: Eminence In Shadow Manga