My little sister is too cute, so I have to protect her!

My little sister and I grew up together in a warm family. We've always spent our time together, and before I knew it, my little sister became extremely cute! Since the start of the semester, she has received more than 30 love confessions from boys she doesn't even know! Most of them just felt disheartened when they were rejected. However, some of them were infuriated and came back for revenge. Thus, it is a duty of mine, her big brother, to protect her with all my might!!!