I'm an S-rank monster, Behemoth, but I'm mistaken for a cat and live as a knight of an elf girl.

【Anime Adaptation Announced!】

Aria, an elven girl, is an adventurer. Her face is so endearing that everyone is captivated by it, and her chest is incredibly bountiful. Cradled in Aria's arms is a small beast... its name is Tama. On the surface, it looks like nothing more than a kitten. But Aria and those around her are unaware that Tama is a reincarnated former human, and that its true identity is not a mere cat, but the infant form of a top-tier monster: a Behemoth――

//Also available on Kakuyomu