Various Japanese animated series based on the manga by Yuzo Takada in Weekly Manga Action.
The various series revolve around Ryunosuke's pet cat who's brain is transplanted into a female android (by Ryunosuke's father and inventor Kyusaku Natsume) body after a accident. This android body allows Atsuko 'Nuku Nuku' Natsume various powers and abilities and becomes a guardian and sister to Ryunosuke. The prototype android body however is was property of Mishima Heavy Industries owned by ex-wife Akiko Natsume who not only wants the body back but also her son. She attempts to get both her child and the android through various means but Kyusaku, Ryunosuke and Nuku Nuku have other plans.
The first OVA series was produced in 1992, All Purpose Cultural Cat Girl Nuku Nuku, and released on VHS and Laserdisc and lasted six episodes.
A 2nd OVA series, Nuku Nuku , was made that spanned 12 episodes and a 3rd OVA, All Purpose Cultural Cat Girl Nuku Nuku DASH!, was released in 1998 that also lasting 12 episodes.
All the series and manga are currently available from ADV Films.