All Purpose Cultural Cat Girl Nuku Nuku is a lesser known anime that's deserves way more love.
The basic premise of the original six-episode OAV is that scientist-dad has split from his wife and her military hardware family business, making off with their son and scientist-dad's android masterpiece.
While they're on the lam (actually while taking a piss), the kid adopts a stray cat.
Unfortunately, the cat dies after they're attacked by one of the wife's attack helicopters.
No problem. Scientist dad implants the brain of the cat into the android and pawns the whole package off as a high school girl.
By the way there are plenty of the traditional anime idioms to be found here, such as the waterfall crying, the laughing eyes, and what not, but the anime on a whole does look pretty good.
Nuku Nuku takes a stand against the wife and her cronies so she, the boy, and scientist-dad can all live like a normal family.
There are mecha, and giant robots, and fairly discrete fan service, and did I mention a near-indestructible high school girl robot with the brain of a cat?
Sealing the deal is the the voice acting of Megumi Hayashibara (as Nuku Nuku) and Aya Hisakawa (as Arisa, the more war-mongering of the two henchmen).
Incidentally, the wife's henchmen are fucking cool, and it's not just the killer helmets.
Episode Three features the mom trying to be domestic and traditional a la Aoi from Ai Yori Aoshi. This episode is especially hilarious. If it has any weakness at all it's that the henchmen aren't in it as much.
All six episodes of the first All Purpose Cultural Cat Girl Nuku Nuku OAV are available on one R1 DVD by ADV. There are some shitty fansubs floating around, and I do know a DVD rip was posted to USENET a few months ago. But c'mon, six episodes on one DVD—it's totally worth it.
There are also later OAVs, but I haven't seen them so I can't attest to their quality. The original OAV, though, is excellent.