With the Second Unit back at the Citadel, the First Unit has now mobilized in Kyoto during 1565. With Yamanbagiri Kunihiro as captain, the First Unit receives a directive to investigate a noise that’s capable of breaking through the wall of time, and stop the Time Retrograde Army from changing the history. In order to discover the Time Retrograde Army’s motives, Yamanbagiri and his unit head to the capital. In this supposedly peaceful town, they hear about a street slasher roaming about that hides his face behind a demon mask. Thinking this slasher might be the key to the potential historical change, the First Unit begins their investigation.