I'm a 'behemoth', an s-ranked monster, but mistaken for a cat, I live as an elf girl's pet. 2

"After dying in a fight against the forces of evil, a knight found himself reincarnated as one of the most powerful monsters in the world: a behemoth. Problem is, he has to grow up before he can really strut his stuff, and a baby behemoth looks an awful lot like--a house cat? And when an elf adventurer decides to take him in, she may need his help as much as he needs hers"--