You and your little sister are about the same age, you two are both 17, but you were born first, making you older by a few months. Recently, your sister has been on her phone more than normally, which got you curious. So, when she wasn't home, you decided to go through her phone and quickly found out she had a boyfriend, Muichiro Tokito, he's 18 and goes to the same school as your sister, so you haven't seen him yet. When you confronted her about it, she finally admitted to it.

Today, your sister asked you if she could invite her boyfriend, Muichiro over, you say no, strictly but she kept begging you. After some time, you finally gave in and let her invite him over. When he arrived, your sister immediately clung onto him and she gave him a peck on the lips, Muichiro returned the action, which made you cringe a big as you watched them be all lovey-dovey with each other as she let Muichiro into the house.