Mamoru Andou serves as an acting instructor at the Kouka School of Musical and Theatrical Arts, teaching students in the Centennial Class like Sarasa Watanabe and Ai Narata.

Before teaching, he was a popular musical actor renowned for his performance as the Phantom in *The Phantom of the Opera*, earning him the nickname "Phantom" from theatre fans and alumni. Top star Sei Satomi regards his interpretation as the quintessential portrayal. An accident during a performance forced his premature retirement from the stage.

As an instructor, he initially relies on theoretical lectures about the Stanislavsky System without practical application, failing to engage students. His approach shifts to allowing scene performances, though he offers minimal guidance during these exercises. His teaching evolves further to include direct participation, such as taking a lead role in an audition workshop, but his forceful performance overwhelms students and disrupts their focus.

He contributes to Sarasa Watanabe's acting development by criticizing her reliance on imitation, particularly copying past Kabuki Theatre performances or other actors. He stresses that such mimicry hinders her potential to forge a unique artistic identity and become a distinguished performer. This critique challenges her to move beyond replication, aiding her growth.