Kyousuke Kousaka

Kyousuke is an average highschooler, has average grades, lives in an average family (upper-middle class with a father, mother and sister), and has average physical features. Currently, he attends an average high school with Manami and he begins the story as a first-year, but he becomes a second-year during the events of the novel. As far as future plans, he intends to attend the same local university as his childhood friend, Manami. At the beginning of the series, Kyousuke and his younger sister, Kirino, have a distant relationship. Kyousuke says that they entered a "cold war" of sorts a few years ago, but the details of this cold war have yet to be revealed.

Kyousuke is a good-hearted character and is extremely loyal to his friends and Kirino. He's willing to take risks for them and help them at any cost.

He and Kuroneko date for a while, but she ultimately breaks up with him. After witnessing his sadness firsthand, Kirino tries to get them back together, but Kyousuke decides not to when they approach Kuroneko and he learns Kirino wants to be the number one girl in his heart.

Later, his parents force him to move out after they express their discomfort in his relationship with his sister. Whilst he is living alone, Ruri, Ayase and Kirino argue over who should take care of him as he needs someone to cook him meals. Eventually everyone agrees that Ayase should be looking after him while he studies as she hates him the most. After the two months, he moves back home and his parents reveal that they knew about it all along and simply used Kirino as an excuse to get him motivated to work.

He eventually develops into a siscon and has impulses towards her, stating that he was beyond cure.