666: Satan

In a future where remnants of an ancient civilization known as O-Parts are highly contested, individuals called O.P.T.s possess the ability to harness their power. Jio, a boy shaped by hardship and driven by a deep trust in money, is unaware of his own latent strength as a powerful O.P.T. and the violent entity within him. He crosses paths with Ruby, and the two form a partnership to search for O-Parts. Their journey raises questions about whether Jio will support Ruby in achieving her goal of becoming a renowned treasure hunter, or if Ruby will assist Jio in pursuing his own, more sinister ambitions.