Former ryokan (Japanese inn) worker, Jin Tono, is reincarnated into a fantasy world with a cheat skill! Excited for his first adventure, he encounters a slime, only to find it shockingly strong! Desperate, he tries to use his cheat ability, but all he can do is produce hot water from his hands?! With zero combat power, Jin is on the verge of death, until a passing female adventurer, Oraria, saves him. In exchange, he swears to do anything she asks. Little does Jin know... He just made a deal with the wrong person. His "hot water" skill isn't useless—it's actually... insanely overpowered?!