In the near future, a young girl, Irisa, wanders into the ruins of and old temple where she meets a strange Old Monk. As they watch the sun go down on the submerged city of post-global warming Kyoto, the Old Monk tells Irisa an old story: Louis, a fugitive from the Crusades, is shipwrecked on the shores of Heian period Japan. Alone and on the edge of death, Louis is saved by a mysterious woman - Amaya, and falls in love with her. He makes a promise to her which he keeps for three years until one day his faith is tested and he fails. Louis sets out on a journey to atone for his sins...