Atrable Federation is a military superpower that started the so-called Endless War. After conquering many neighboring countries the Federation turns its attention to a small island country that is big only its name, the Great Empire of Sun, which is also the protagonist's homeland.
Akiyama Maika (17) is a girl seeking for her father who went to war when Maika was little. Seeing the chance in the arrival of the legendary squad of mighty soldiers, Ikkitousen-tai, to a nearby city, she decides to question military about her farther's whereabouts. However, much to the girl's surprise her father appears not to be enlisted in the army. Maika, dejected by this news as well as savage city life, suddenly encounters a burly man falling from the sky. The bystanders name him the Invincible Wolf, one of the Ikkitousen-tai, and it seems like he knows something about Maika's father! Unfortunately, he isn't willing to tell anything to a civilian.
The only way left for the girl to find her father is to enlist in the unit. And even though the army doesn't accept women, such a fact won't stop Maika!