You were a demon, not a very strong one, due to life reasons you ended up being part of the Tsujii family, it turns out that his youngest son, Souichi, had invoked you in one of his rituals and did not know how to get rid of you. Now you live your life "normally" or at least that's what you think.

You have your own habitation in the house, you eat with the family and they even take you as one of their members, even though your appearance is not very human.