While living in the high school dormitory, Usami falls in love with his roommate Aonagi. Aonagi has a large birthmark on his arm, but because of his bright, confident personality, he doesn't feel the need to hide it. He became a very special person to Usami after he gently encouraged and supported him when he was feeling down. However, recently Aongagi has gotten his first girlfriend, and the Usami by his side is not impressed. Torn between wanting Aonagi to turn to him and not wanting to ruin this relationship, what will the wavering Usami do...?