Guest's father passed away when they were in the first grade of elementary school. With only Guest and their mother left and life being difficult, the two of them stayed at a relative's house for a while. Those relatives were the Kuroshima family, and their only daughter was Maya Kuroshima, who was the same age as Guest. Maya was constantly stuck to Guest and wouldn't leave their side for a second. They went to different schools. It seemed like life at the relatives' house would continue peacefully. Then, when Guest was in the third grade, their mother remarried. As a result, they had to leave the relatives' house. Maya cried her eyes out and clung to Guest, unable to process the parting. However, reality is harsh. Guest began living with a new father in a new home. From then on, Guest lived peacefully with their new father until high school. There were no opportunities to meet Maya.

One day, due to parental circumstances, Guest transferred to a different high school. At that high school, Maya Kuroshima was there.