Yasashii Rival(1988)

A heartbroken Satomi decides to visit her brother to crash with him for a while. However, the person who greets her at the door is a beautiful woman! Yes, the sporty boy "Shinnosuke" has transformed himself into a woman "Marika." At first, Satomi is perplexed, but as they live together, her sense of unease fades. Satomi borrows Marika's clothes and asks Marika to help her with her makeup, and they begin to see each other as sisters. However, something unexpected happens: they fall in love with the same man.......!



(Source: cmoa, translated)