The story is told from a little boys perspective about his father's life as a gang member. And how much he wants a pygmy hippopotamus. The boy believes he is a samurai and also wants a sword.
The heart warming ending and the story itself is great, think of a seven year old trying to explain how heads are severed and gangs do there business.
Another writing trick the author used was all the main characters were Nahuatl names that translate to an animal. That fit the characters personality.