Mamahaha no tsurego ga moto-kano datta 3 (Kadokawa Sneaker Bunko) [Light Novel]

[Machine Translation] Mizuto and Isana are back to being best friends without any problems, even though Isana's confession did not come true. Yume's heart was still troubled by the distance between the two, but there were two people she could not understand any more than they did. They are Gyotsuki Minami and Kogure Kawanami. Although they have known each other since childhood, they quarrel every time they see each other. Yume wants Akatsuki and Kogure to make up, and Mizuto, sensing their past, gets Isana involved to play a part. The upcoming study camp. Gyotsuki and Kawanami have to face their black history. They are forced to call each other by the nicknames they used to call each other back then and play lovers. It's just a "punishment game," but they can't help but be aware of each other - they are former lovers, too!

いさなの告白叶わずも、すんなりと親友同士に戻った水斗といさな。相変わらず近い二人の距離感に、心がざわつく結女だったが―そんな彼ら以上に、理解できない二人がいた。南暁月と川波小暮である。幼馴染み同士なのに、顔を見る度にいがみ合い...。暁月たちの仲直りを望む結女、そして二人の過去を察した水斗は、いさなを巻き込んで一役買うことに!?きたる勉強合宿。かくして暁月と川波は、黒歴史に向き合うことになる。あの頃のあだ名で呼び合い、恋人ごっこをさせられて。それはただの“罰ゲーム”なのに、どうしてもお互いを意識してしまうこの二人も―元恋人同士なのである!!