Night after night, Elva steps forth into the black sea, sword in hand, to drive back the creatures that surge from the waves. Elva is one of the "kannagi", warrior priests chosen by the divine to protect the island. With his snow-white hair, unaging youth, and black-stained limbs — proof of the corruption that gradually takes the life of every kannagi — the local people fear and shun him... at least until his path crosses with that of a boy named Alto. Enraptured by Elva's strength and lonely soul, Alto swears to serve him and free him from his cursed fate.

After eight long years, Alto has grown into a capable and fearless young man, unwavering in his devotion to his kannagi. Elva had long ago resigned himself to an early death — but somehow, Alto's presence seems to be gradually healing him of the black sea's corruption...