From ADV:

When inventor Kyusaku Natsume transfers the brain of his son Ryunosuke's cat into a top secret android body, he doesn't lose a family pet...he gains a daughter!

Nuku Nuku may appear to be a teenage girl, but her cute and cuddly exterior hides both the superhuman strength of the world's most advanced android chassis and the lightning-quick senses of a domestic feline. She’ll become the sister Ryunosuke never dreamed of, and she’s on a mission to save her new family from disaster!