If I were to have a pet from anime, I would definitely choose Ryo-ohki! She is so adorable, and loyal to a fault!
Just keep a healthy stock of carrots and she is good to go! She is intuitive and helpful, and so adorably sweet!
Plus there's that thing where she can transform into a BATTLESHIP. That's pretty nifty too. Mmeeooooowwwww! @VinMcCarthy