18+ Lime-iro Senkitan: Nankoku Yume Roman

With the battleship Amanohara seriously damaged and in need of repair, it lands on an island where a Gogyou festival has just begun. Shintaro Umakai and his five female students, known as Raimu Unit, enjoy a period of peace on the island. However, the enemy still pursues them. Umakai and his unit deal with the enemy while the five girls try to draw his attention.

(Source: ANN)