Since ancient times, peace treaties have been made between humans and monsters. However, there is no end to small troubles, and sometimes there are victims. The [Kyoto Prefectural Police Yin-Yang Division] responds to such incidents. Yui Shigami, who was assigned there as a newcomer, spends her days training. One day, Kagami is summoned to the section chief's office. Due to the increasing number of violent and mysterious incidents in recent years, it was decided that the human side and the monster side would conduct joint investigations. And then, a special mission is given to the newcomer Shigami to investigate the incident together with the "collaborator" of the mysterious side. That was the beginning of many unconventional on-site investigations with an eccentric partner!A monster battle fantasy by a novice Yin-Yang cop and an outlaw supernatural sister's bumpy buddy begins here!