All of a sudden, there were children who were born in Japan with special abilities. They were segregated to a school located on Tendoujima, an island in the southern sea. Meanwhile, the relatively normal Yorito drifted on to the island after being swept by the waves from his adventurer father’s raft. After Himeno saved his life with artificial respiration, he ended up transferring into the Tendoujima Gakuen. Since he was suspected of being a spy, he accepted a request to explore the dungeon where monsters dwelled in order to establish his innocence. He enjoyed a pleasant life with the girls at the school, getting to know them better and solving their worries, but soon he became involved in various events while investigating the dungeon.