A crisis is approaching, and meanwhile, the higher-ups are plotting behind everybody's backs. Plans of a massive comet interception mission involving both Comet Blasters and Meteor Sweepers' MiG-31MS and TSR-2MS are being prepared. But will the plan succeed? Is it tears of sorrow or laughter and joy that await the team of four beauties from Shimojijima Base?

When Imperial forces attack the small border town of Bruhl, Welkin Gunther, son of late General Belgen Gunther, is forced to fight for his life alongside Town Watch captain Alicia Melchiott. Along with Welkin’s adopted sister Isara, the three escape to Gallia’s capital and subsequently join the country’s militia forces. As members of the newly-formed Squad 7, they must work to repel the invading Imperial forces and discover the true purpose of the invasion itself.

The story is set in Shanghai in 1931, when the Imperial Japanese Army has been dispatched to mainland China due to the relatively recent First Sino-Japanese War, Russo-Japanese War, and World War I. In this cosmopolitan city of intrigue, there is a special military spy organization called “Sakurai Kikan” that has since been buried in history.