Ryunosuke Natsume has no idea his household helper is really the super sexy hero Cat Girl Nuku Nuku, he just feels lucky to have the lovely girl so close. Nuku, on the other hand, while trying to take care of her newly adopted family, battles with the temper of Ryunosuke's mother, Nuku's lost memories and the evil that lurks inside Mishima, the most powerful company in Maneki City! As Mishima unleashes new and more terrorizing weapons in an attempt to take down Nuku, placing Maneki City in a clear and present danger, Nuku faces the ultimate choice: save herself or the people she loves!