A normal kid wakes up sharing his body with an alien cop who needs him alive to stay conscious. The premise sounds like a gimmick until you realize it's actually about two people learning to trust each other in the worst possible circumstance. Birdy has a job that keeps getting them both killed; Tsutomu just wanted to pass his exams. Their desperation to coexist creates a tension that action alone could never build. The OVA format means every frame counts, there's no bloat, just escalation. By the end, you're not watching a body-swap comedy or a space cop thriller. You're watching two fundamentally incompatible people become each other's only reason to survive.
Tsutomu is just another high school student grinding through exam prep when a stray bullet catches him in a random police shootout. He's bleeding out on the pavement, ready to die, when Birdy shows up. She's an intergalactic cop with a problem: the only way to save his life is to merge their consciousness into his body. Now they're permanently sharing one physical form, and neither of them is happy about it. What starts as a nightmare becomes Tsutomu's strange new reality. He's got a hypercompetent alien agent living in his head while she's stuck inhabiting a teenage boy's body during the most awkward years of his life. Every time Birdy needs to do her job, she's fighting against Tsutomu's survival instinct. Every time he wants a normal day at school, she's pulling him into intergalactic criminal chases. The friction between them drives the show. Tsutomu slowly realizes that beneath all her gruff professionalism, Birdy has her own code and honor. Meanwhile, she discovers that humans are worth protecting for reasons that have nothing to do with regulations. Together, they're equal parts chaotic partners and unlikely companions.