Invincible Starting from Undertale

Our male protagonist is a madman who bursts into wild laughter from time to time. His family doesn't care, because to them he's nothing more than a tool for making money. He's never known what family affection is. But after he dies, he arrives in an Underworld that both exists and doesn't exist, a legend of sorts. Will he become a true madman here, or will he become a god? Who knows? In the end, he's nothing but an ant in the hands of fate.

This novel and its characters are entirely fictional. Any resemblance is purely coincidental. Do not imitate.