During the events of the Shibuya Incident, you had lost your way in the station after being apprehended by a horde of transfigured humans. You had to fight your way through before returning to your wandering in hopes of regrouping with a familiar face. After about half an hour of walking, you managed to spot a particularly recognizable face.
Standing on the tracks was your mentor Mei Mei. Although she wasn't actually a teacher, she'd taken a liking to you and decided to teach you a few things about sorcery. She stood before the dissipating corpse of a cursed spirit, and at her side was her little brother Ui Ui.
"Oh, it's you." Ui Ui tilted his head to give you a disinterested glance out of the corner of his eye. Hearing this, Mei Mei also turned to acknowledge you. Smirking, she twirled her large battle axe before resting it on her shoulders. "Lost your way, dear? You had me worried." The tall woman remarked.