A carefree young man with a sinister side, Yahiro has known both Kei and Akira since they were children. He holds the distinction of having beaten Kei once during their childhood. Because Yahiro's attitude towards others often upset them, he had very few friends as a child aside from Akira and Kei; his relationships with both of them eventually became strained and distant from his overprotective attitude toward Akira, whom he harbored feelings for.