Yukimichi was obsess with being with haru seemingly that when natsu came into the picture, yukimichi end up going mad and crazy for haru like a yandere way but not in love with him. He seem to want haru to only look at him and pay attention to him alone like before when natsu came. When haru didn't kill him and left with natsu, His power end up going away because he want Haru all to himself, to only be with him, but when haru left, his emotional string of obsess seem to shattered. In the end he end up broken emotionally. I really hope they make a sequel where yukimichi escape and tries to destroy haru and natsu relationship between them and to see how that goes
It started off with the oni lady but she wasn't there °^°