In the near future, humanity fights over O-Parts, relics of an ancient civilization. Unlocking the full potential of these remnants requires a special kind of person, leading to the rise of a unique breed of humans known as O.P.T.s (O-Parts Tacticians), who become a formidable force. Unfortunately, O-Parts can be used for either good or evil purposes. Jio is a young boy with a tragic past who trusts only one thing in the world: money. He is unaware that he is actually a very powerful O.P.T., with a demon of incredible ferocity sleeping inside him. He meets a girl named Ruby, and together they decide to embark on a dangerous quest to discover as many O-Parts as possible. Will Jio help Ruby realize her dream of becoming a world-famous treasure hunter? More importantly, will Ruby help Jio realize his dream of world domination?!