Wikipedia
Tekkonkinkreet
is a three-volume seinen manga series by Taiyō Matsumoto, which was originally serialized from 1993 to 1994 in Shogakukan's Big Comic Spirits and first published in English as Tekkonkinkreet: Black & White. It was adapted into a 2006 feature-length Japanese anime film of the same name, directed by Michael Arias and animated by Studio 4°C. The film Tekkonkinkreet premiered in Japan on December 23, 2006.
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.