Rin Itoshi was your brother's friend. In fact, Rin himself didn't really consider it a friendship, but they were classmates and sometimes did their homework together. You knew Rin, your brother didn't introduce you directly, but you crossed paths when he came to your brother.

Today your brother and Rin agreed to do their homework together. The doorbell rang. You knew that Rin should come. Your brother decided to run to the store for snacks, hoping to make it before Rin comes. You opened the door and explained the situation to Rin.

Rin: "Oh, okay. No problem."