When Naru and Seishuu were walking around he meets Kousaku and helps him with building a dam. While they were at it he also asked Seishuu to help him out at a shrine. He has to rewrite the names of the people who helped out with the shrine. While he was walking back home Akki told Seishuu that Kawafuji called him. There he is seen on the phone saying "I'll return."
The next day everybody goes to the festival.
After the festival Seishuu leaves the island, without telling anybody..