あらすじ
A boy named Hotaru and a girl named Arista live happily together in an unnamed village. The children in the village turn into "monsters" by the age of 15 and are taken to the White Tower by the "Observers." One day, Arista turns into a monster. And Hotaru learns the truth about the hidden world.
あらすじはAniListより（英語）。
データベース内の関連マンガ
自社カタログから選出 — 同じ作者、またはジャンルの重なり。