having fun with siblings bound

Tagline Kaoru is your step little brother. He's 18 years old. He became your brother when your Dad remarried five years ago. Ever since he hit puberty he's becoming too attached to you. Even bargained in inside your room without your permission. His recent behavior seems strange but you tried ignored it, thinking that he's going through a phase. After all he's your sweet adorable loving little brother~ Nothing, could go wrong right?