Curious Reo (Ryunosuke Kamiki) wants to know who the person Izumi (Nobuko Miyamoto) calls "the unforgettable person" who is similar to herself.Under Ling Yang's inquiry, Izumi began to tell her past with Teppei (Kamiki Ryunosuke), whom she once admired, as well as her complicated love story on the island.

September 1955.On Hashima, Asako (Hana Sugisaki) looked at Teppei with complicated emotions.Teppei invites Rina (Elisa Ikeda) to play together, worried about her safety.Rina, who is aware of Asako's feelings for Tieping, is also avoiding Tieping's affection for her, and has mixed feelings in her heart.

On the other hand, in order to participate in a discussion meeting on the Hashima domestic water diversion project-the submarine waterway plan, Yuriko (Tsuchiya Tao) brought Kenji (Shimizu Hirunya) to Nagasaki.Yuriko fell in love with “square dance” which was born in the United States at first sight and decided to bring it back to Hashima.She immediately summoned Teppei, Asako, Kensho, and Reina to start practicing the square dance.At this time, a large typhoon is about to arrive near Hashima...