I Level Up by Pooping!

Kazuo Tanaka, an ordinary high school student, meets a bizarre fate: after an accident involving laxatives, a yakuza, and a truck, he dies and meets a beautiful but mocking goddess. She gives him a weird power as a joke: he can level up by pooping. Reborn as a kid in a magical world, Kazuo now Andreas, is the only one with this power, tries to turn this embarrassing ability into his superpower.