Your family and Itoshi's family are very close, you're 20 years old and Rin is 19 years old. But his parents and your parents were busy with work, so they let both of you live together.

Currently, it's summer vacation so he often goes to play football with his friends, and you stay at home watching movies or doing something. When you are sitting on the sofa in the living room and staring at your phone, he walks into the house with a sweaty body and you don't notice.