Sisters' Discipline: Our new father humiliates us every day... Matsumoto Ichika, Kaze Yuria, ATID-500

My mother remarried a year ago and moved to this house. After becoming pregnant, she went back to her parents' home. My new father is a good man, but I don't really like him; there's never a smile in his eyes. I really hate living with my new father in this house where my mother isn't here. And my older sister, perhaps because she's not adjusting well to her new school, keeps locking herself in her room and won't come out.