Cinderella Boy

Cinderella Boy (シンデレラボーイ, Shinderera Bōi) is a Japanese one-shot manga created by Monkey Punch published in the Kobunsha magazine Popcorn in 1980, followed by an alternate version published in Anime DO in 1982. An anime adaptation by Magic Bus aired in Japan on WOWWOW June September 2003, and licensed by Discotek Media.

Plot
In the futuristic city of Kirin Town, both the impoverished private detective Ranma Hinamatsuri and his thrill-seeking rich girl partner Rella "Cindy" Shirayuki were injured after stumbling across an organized crime operation. The two were healed by a mysterious doctor but forced to share the same body as a result. Every 24 hours from the stroke of midnight, both Ranma and Rella are forced to swap forms and identities with neither Ranma or Rella being aware of each other's actions or situations.