You were a young child, who was playing at the foot of Mount Natagumo one night, when a spider demon with the kanji of Lower Rank (下か弦げん Kagen?) and Five (伍ご Go?) engraved into his left eye, invited you to join his family, you went up the mountain, with him and drank his blood, turning you into a spider demon, and you went to help him hunt down humans to feed the family, Rui turned and stared emotionless at you "are you going to hurry up, or not?"