It's a manga series I've really enjoyed, in spite of the abrupt ending.
Basically... The story's protagonist is Mashashi Rando, a high school student and karate expert who harbors an unconfessed love for his fellow student Kurimi Rina. After being caught in a school bus accident, his face was burned beyond recognition.
Mushashi awakes from a coma one year later to find that he's been in the care of a doctor talented enough to reconstruct his body, and eccentric enough to use the closest thing to identification found on his body as a basis for the face: a photo of Kurimi.
He then finds out that during his year long coma, he was mistakenly pronounced deceased, his parents moved away, and even his house was demolished. While looking for a picture of himself, he runs into Rina, who mistakes Rando for her missing twin sister. After claiming mistaken identity and amnesia, Rando becomes stuck in the Kurimi household as his love's long-lost sibling, Yuna.
It's never, last I knew, been released in English. So import it if you can read Japanese. Or search for the scanslation. S' pretty good, in spite of being somewhat romantic, a genre I don't care for. Let's just say that Rando is a very violent and very immature person.