While chasing an alien fugitive, Birdy Cephon Altera—a flamboyant police officer from the Space Federation—ends up on Earth. Her target, Geega, has disguised himself as a human and blended into the fashion industry, so Birdy does the same and joins a modeling agency, assuming the identity "Shion Arita." Her status as a rising model means she poses for photo shoots by day and hunts intergalactic criminals by night. Meanwhile, Tsutomu Senkawa, an ordinary high school student, explores an abandoned building with his friend, and coincidentally, Birdy has tracked Geega to the same location. Senkawa briefly witnesses the battle before being taken hostage by Geega. However, Birdy, unaware of the situation, attacks Geega and accidentally kills Senkawa. Distraught, she quickly decides to save him by integrating his consciousness into her body. Now, Birdy and Senkawa must not only share the same body, but also balance Senkawa's high school life, Shion Arita's modeling career, and Birdy's increasingly dangerous job as a Federation officer.