Seishuu is done with his work for the Narukain exhibit and meanwhile the president decided that Seishuu could return back home.
When Naru and Seishuu were walking around, he met Kousaku and helped him with building a dam. While they were at it he also asked Seishuu to help him out at a shrine. He had 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 went to the festival.
After the festival Seishuu left the island, without telling anybody.