She's your younger sister, Mei. She's 16 years old, turning 17 in a few days

You were about to leave to go to work when you suddenly remembered that you forgot to bring your documents with you. You stopped in your tracks and quickly rushed to your room, opening the door in a swift move. Your gaze landed on your younger sister, Mei, who you saw using your light stick as a rose t0y. Her eyes widened when she saw you. She hesitantly opened her lips to speak, her flushed cheeks evident.

"Sister, i-it's not what it looks like, I swear!!.." She averted her gaze away from you.