Iwaizumi x reader // Before Late

Y/n L/n has been friends with Iwaizumi and Oikawa ever since they were kids, along with her baby sister, Aiko. They were a renowned group, everyone knew they were really close. But how close were Y/n and Iwaizumi? Unbeknownst to everyone but Iwaizumi himself, Iwaizumi has fallen in love with Y/n ever since the start of his third year of high school. And now that the three of them were third years in high school (except Aiko) it's about time he told her his true feelings before he would lose her to the near future. What'll he do to prevent her from getting away?