Angel's Feather: Kuro no Zanei

A kingdom of white-winged beings lived in peace until a mutant black-winged clan appeared and began using magic the white-wings lacked to seize power. The king and queen were defeated and consumed by darkness. Their young son was hidden in the human world by a loyal confidant. The king's younger brother had already abandoned the kingdom years earlier — having fallen in love with a human woman, a forbidden act — and was hunted down and killed by the black wings while protecting his wife and their newborn twin sons. Years pass. Shou Hamura, the national kendo champion, transfers to an elite all-boys school. He becomes convinced he has spotted his long-lost younger brother Kai, who flatly denies it. Strange phenomena begin connecting the school to a magical realm called Winfield. Reuniting with his old friend Naoto and meeting new companions — each with particular abilities — Shou starts to understand what he has inherited, and what it will require of him.