Angel's Feather

Hamura Shou enrolls at Yuusei Academy, where he meets Misonou Kai, a student about whom the headmaster shares some information. Shou becomes convinced that Kai is his long-lost twin brother, separated from him at a young age. This conviction is strengthened after a mysterious earthquake transports Shou and two other students to a new world, where he discovers he has great, white wings that emerge when he's attacked by a monster.