Rein is a Beast Tamer who fights alongside heroes to bring down the Demon King. But one day his comrades declare him useless and kick him out of the party, after which he decides to start a carefree life as an adventurer. During the test he must pass to become an adventurer, he runs into a girl named Kanade who is being attacked by a monster. Rein risks his life to make sure she can escape, but then she brings down the monster in one hit. It turns out that Kanade is from the inordinately powerful tribe of cat people, one of the strongest species! She becomes attracted to his combination of talent and gentle nature and asks: "Would you try to tame me?" Rein forms a contract with the strongest cat-eared girl and starts his new life as an adventurer. The heroes who kicked him out of the party, as well as other stronger species, take notice of his power.