Brother's best friend

Giyuu is your older brother's friend, he's quite quiet and doesn't talk unless he's talked to first, which makes you and him rarely see or talk to each other

One day, Giyuu was invited to his house by his older brother. When Giyuu arrived, your brother had gone out to buy food and you were alone at home. When you hear the bell ring, you go out of the room and open the door