The story takes place in the fictional city of Takaramachi (Treasure Town) and centers on a pair of orphaned street kids – the tough, canny Kuro (Black) and the childish, innocent Shiro (White), together known as the Cats – as they deal with yakuza attempting to take over Treasure Town. (Wikipedia)

An interesting article about the artistic influences on the movie – Taiyo Matsumoto and Michael Arias – Tekkonkinkreet Influences