Cat Soup (also known as "Nekojiru-so" [ねこぢる草]) is a film adapted from the works of the late manga artist Nekojiru. The film was released in Japan in 2001, then came in the US (through a DVD only release) on October 9th, 2003.
The film was directed by Tatsuo Sato (who also directed, "Nadesico: Prince of Darkness").
The main character, a cat named Nyatta, embarks upon a journey to save his sister's soul, which was ripped in two when Nyatta tried to save her from Death. She trails after him, brain-dead. They encounter many brilliant, mind-bending situations, beginning with a disturbing magic show.