Pretty Face(2002)

When his school bus crashes, teenage karate star Rando is sent into a coma. A year later he wakes up to find that his disfigured face has been reconstructed in the image of the girl he has a crush on! Not knowing what Rando originally looked like, the mad plastic surgeon Dr. Manabe used a photo in Rando's pocket as the model for his reconstructive surgery. Abandoned by his friends and parents, the all-new Rando is mistaken for his would-be girlfriend's long-lost twin sister and adopted into her family. Can he put aside his feelings and be a good "big sister" to Rina...when he's still a teenage boy from the waist down?

(Source: VIZ Media)