Because it felt so natural. In a casual conversation, many things may happen and some of it leads from one thing to another. It can even be a great change in different relationships and a big impact on one's life. Well, that is what happened for the girl named Fujiwara Chika and a guy named Ishigami Yuu.
A place no one knows them, a world only they know of and a situation they can only share together. Gojo and Makima treasured it so but their time will soon come to a close. The only thing they can do is hope for a better future because they both are not ready to let go just yet.