Tansang Loop is a space station with a population of two million, officially speaking. But really, it s thrice more, including the cyborgs and androids. Io is a Rohm Model Five, a cyborg made with a biomechanical brain and synthetic muscle. While on a routine spacewalk, Io stumbles upon the body of a murdered detective and improbably, both Io and the detective are Model Fives. Io tries to solve the detective s last case in order to find out who killed him, but in doing so, may reveal that their lives are more interconnected than meets the eye.