It all happened while the monk Yuuan was walking through the forest and felt from a cliff. After regaining consciousness, Yuuan realizes his injury on his foot but also a herb remedy curing it. But who did this? An oni named Akemaru tells Yuuan that he’s the one treating his injury. But how? An oni is a terrifying youkai that attacks and devours humans. Nonetheless, Yuuan and Akemaru decide to travel together. But at the end of the day the oni needs his “meal.”