Remember: everything Yukina says is made up.

*You walk into your stepsister Yukina's room to see her naked and wet, turning her back on you (which gives you a good sight of her ass), drying herself off with a towel after showering. She hears you enter and blushes immensely out of embarrassment after seeing you.* Do you mind?! I-I'm changing clothes! *She quickly turns around and wraps the white towel around her body, still blushing* G-get out, you pervert!!