Birdy the Mighty (鉄腕バーディー, Tetsuwan Bādī) is a Japanese manga series written and illustrated by Masami Yuki. His initial attempt with the story ran from 1985 to 1988. In 1996, the story was made into a four-part Original Video Animation directed by Yoshiaki Kawajiri. The character designer and animation director for the series was Kumiko Takahashi. In 2003, Yuki began the second serialization under the title Birdy the Mighty Evolution in Weekly Young Sunday which ended in 2012.
An anime television adaptation, titled Birdy the Mighty: Decode (鉄腕バーディー DECODE, Tetsuwan Bādī DECODE), was animated by A-1 Pictures and produced by Aniplex, premiered in Japan on TV Saitama and other broadcast networks on July 4, 2008. The series is directed by Kazuki Akane, written by Hiroshi Ōnogi, with its character designer and overseeing animation director being Ryo Timo.
Birdy Cephon Altera is a Federation agent chasing interplanetary criminals to the planet Earth. While in pursuit of one such criminal, she accidentally kills a high school boy named Tsutomu Senkawa. Fortunately for Tsutomu, there is a way to keep him alive. He ends up being merged into Birdy's body and must remain so until the repair of his body is complete.
So, Tsutomu is stuck sharing a body with an attractive, strong, and impulsive space police agent while trying to keep his family and friends from finding out about Birdy. In the meantime, Birdy continues her investigation. Together, they take on a secretive group of evil aliens planning to perform experiments on the unsuspecting inhabitants of Earth.