Tsutomu, an ordinary high‑school student, is preparing for exams when he inadvertently interrupts a police pursuit. He is caught in the crossfire and is on the brink of death when Birdy, a young interplanetary police agent, arrives. By merging her consciousness with his, Birdy saves his life, and from that moment the two share one body. Together they must navigate their new coexistence as she continues her duties of capturing criminals and saving lives across the galaxy.