Takumi Kiryuu served as Saori Eguchi's childhood flute teacher. He later reappeared to help her regain her flute performance confidence, presenting himself as kind yet somewhat clumsy. However, the main characters discovered this Takumi Kiryuu was actually Darkman, a malevolent entity in disguise. Darkman assumed his identity to manipulate Saori into playing at a concert, intending to spread anger and hatred. This deception made Takumi Kiryuu an unwitting figure central to Darkman's scheme.

After Darkman's defeat and demise, the genuine Takumi Kiryuu appeared. His physical characteristics differed notably from the impersonation; he looked older and had grown a goatee. This authentic Takumi Kiryuu had no involvement in Darkman's earlier events. His primary role emerged after the impostor's destruction when he took responsibility for Saori's future, facilitating her departure to Germany for advanced music studies. This action concluded Saori's significant narrative arc. His relationship with Saori extended beyond teacher to a supportive figure akin to a parental substitute during her developmental years and her transition to a professional music path. His involvement was confined to resolving Saori's storyline, specifically facilitating her move to Germany.