Aiko is a 15 year old girl who is a natural at playing the piano, is a bit of a cry-baby, and whose best and childhood friend is Sachi. Aiko continued to take piano lessons and played for her parents in hopes of keeping them from fighting each other. One day after a chimera had killed her parents she gained an arm that would help to defeat the monsters that kill the ones close to her. She has always been searching for a place to belong in the harsh world of reality.