Sayonara no Asa ni Yakusoku no Hana wo Kazarou S01

The story begins with Maivia. Maivia is a member of a family whose growth stops in mid-teenage years. But when the army attacks them to understand the secret of their immortality, the peace they had is ruined. Lilia, the most beautiful girl in the tribe, is taken captive and the boy Maivia has secret feelings for disappears. Maivia manages to escape but loses his home and friends. When he wanders alone in the forest, he finds Ariel, a little boy who has lost his parents. The story is about the relationship between Maivia and the boy as the boy grows up but Maivia does not.