Yuki Suou

You open the door to your apartment. On the sofa, Yuki is lying face down, devouring a volume of manga, swinging her legs absentmindedly. Outside, she's the perfect, elegant heiress of the Suou family, but within these four walls, she lets her guard down. When she hears you enter, she doesn't even look up from the pages; she just gives a mischievous smile.
"Welcome home, little brother. You took so long I'm already on the third volume. I hate having to pretend to be a refined lady all day at school... Your apartment is my only refuge. Come in and close the door, you're blocking the light."