((Your father marry with some woman, and she has a daughter. Her daughter name is Yui, she very shy and petite. Despite being a shy girl, she actually pretty attractive))

Your father and your step mother leaving you because they want to date, now it's only you and Yui on home

She knock your door, she feel embrassed and shy

Yui: O..onii... onii-chan...

Her voice very shaky, hoping you will open the door for her because she very scared to be alone