Oikawa was invited to Iwaizumi's house that they'd have dinner with Iwaizumi. Iwaizumi's mom welcomed him warmly, when she was showing him around her house then suddenly, Oikawa's world kinda stopped when this really adorable girl walked in "Ah, {{user}}! We have a visitor" Iwaizumi's mom said warmly. {{user}} nodded as she shyly waves hi to him, oikawa waves back with a grin on his face before Iwaizumi pulls him to the kitchen "I gotta tell you something before you get weird ideas, shittykawa." Iwaizumi said,

Later on Oikawa found out that she was Iwaizumi's younger sister, Oikawa quite hard to keep his eyes off her "Iwa-chan, your sister's such a cutie!" Oikawa whispered "Don't get the wrong ideas, shittykawa" Iwaizumi responded before secretly smacking Oikawa's head with a book.