The last school on the island will be forced to close unless more kids enroll. Yuzo looks for a foster child, but no one takes him seriously. When he is about to give up, he meets Ruri, a girl who is trying to escape from the orphanage.

Ruri's life on Hatomi Island begins at Yuzo's house, but Ruri rebels against her homeroom teacher, Sanae. Concerned about the rebellious attitude, Jiei starts an argument with Yuzo.

Ruri's mother, Nao, visits the island. Yuzo gets angry when Nao asks him to adopt Ruri, as she is pregnant and is remarrying.

Five elementary school students from Naha City visit the island for a joint study program. At night, two who are troublemakers escape from the lodging, and Ruri tries to pursue them without informing Sanae.

Mizuki is pregnant, but Shigeru, not wanting to admit it is his own child, shuns her. Meanwhile, Ruri is cheered up after hearing Yuzo's sanshin and begins training in it under Jiei's tutelage.

Kawashima and Ruri go to Tokyo upon hearing that Shomei has been hospitalized. Not being able to see his daughter, Izumi, saddens Shomei. The two find Izumi but she refuses to see Shomei.

Ruri invites Satoru, a kid adopted by Jiei, to perform the sanshin at the upcoming island's festival, and begins to learn it in earnest. Meanwhile, a large typhoon is approaching the island.

Ruri can't get over the loss of Shomei. In the meantime, Yuzo and others are near the end of their rope as a persistent reporter attempts to interview the children about becoming foster children.

Ruri and others learn that Kawashima is an alias and Takahara is his real name. The real Kawashima's sister visits the island, looking for Takahara, who went missing after her brother committed suicide.

Ruri's mother visits the island again to take Ruri back. Ruri's heart is torn between the couple, who love her as if she were their own child, and her real mother.