Free Collars Kingdom(2002)

Cyan is a teenage cat (in cat years!), and when his beloved young master falls ill, the parents abandon Cyan in the basement of a luxurious apartment building. Now Cyan finds himself smack-dab in the middle of the biggest feline territorial battle in Japan.

While waiting for his owner to return and reclaim him, Cyan has to brave the attacks of vampy Siam and the beautiful killer Kline. He also must try to fit in with the group of oddball strays who reside in the basement, a cat gang named the Free Collars!

(Source: Del Rey)