Teacher Kawashima Haru takes a position on a remote island off the coast of Hokkaido, where she takes charge of six students. However, she is later forced to leave after an accident occurs. 20 years later, Haru learns that one of her former students has committed a crime, and eventually returns to the island once more.

Teacher Kawashima Haru takes a position on a remote island off the coast of Hokkaido, where she takes charge of six students. However, she is later forced to leave after an accident occurs. 20 years later, Haru learns that one of her former students has committed a crime, and eventually returns to the island once more.