Two years ago, the death of Naoto Watari's parents left him as the sole caretaker for his younger sister Suzushiro "Suzu" Watari and forced him to move in with their aunt. So devoted is he to Suzu that he refuses to join clubs or even hang out with anyone, earning him snide comments and the title of "siscon" at his new school. But as long as Suzu is safe and happy, Naoto doesn't care what everyone else says. However, his sneering classmates may turn out to be the least of his worries. The sudden transfer of a girl named Satsuki Tachibana brings back traumatic memories from his past-a past she had a hand in making so unpleasant. Nasty secrets, unknown to Naoto, begin to surface with her arrival, threatening his new life.

Blatt Meister Ascheriit was slain by his allies and was branded a traitor. Now, 20 years later, he is back with a new name, Köinzell, and a thirst for vengeance. Köinzell arrives at the border wall, Thousand Stonespears, at the Border City of Rielde-Velem. Here, he sets about infiltrating an underground monastery of corrupt monks.

The story of a lower-class ninja assigned to a high-class mission.