Pretty Face

Due to a terrible bus accident, Randoh (the main character) wakes up one day to discover he has the face of an attractive girl thanks to a rather perverted plastic surgeon. But not just any girl's face--it's the same girl that he has a crush on. To make matters even worse, he runs into the girl and she thinks it's her long-lost twin sister. When Randoh moves in with her (quite willingly) he is torn between helping out this girl by pretending to be her sister, and wanting his old face back.
(Source: Akatsuki-Manga)