In order to seize the precious engine held by the palace country where the protagonist and others are located, the neighboring countries began to invade increasingly fiercely. In order to meet the enemy, Miyakuni was forced to convert the ceremonial double-seat flying boat "Simoun" into a combat warship. Ungendered "shrine maidens" were also needed to be sent as pilots, and as a result, they became members of a combat squad known as "coru".　　The few girls who manipulate "Simoun" are called "Simoun シヴュラ (Sibella)" because they have special abilities that allow them to choose when they become adults. However, due to the outbreak of the war, their excellent talents had to be used in the operation of "Simoun", in other words, they were forced to remain in the "girly stage......