Mónica Tamura, named Eriko Tamura in the original Japanese version, is the only child of Yuusuke Tamura, chairman of Tamura Productions, and former idol singer Minako Tamura. Born into privilege, she displayed natural singing talent early on, but her parents discouraged her from pursuing music to preserve a normal childhood.

Her life transformed when a car accident killed her father and left her mother comatose. Placed under the guardianship of her uncle Kosuke Tamura, she defied both her parents' wishes and her uncle's active sabotage to pursue a singing career as a tribute to her parents.

Initially fragile and prone to tears under pressure, she developed resilience. She endured industry exploitation, manufactured tabloid scandals, and her uncle's manipulation. Rival Rei Asagiri assaulted her twice; during the second attack, Mónica retaliated in self-defense but instantly regretted it, reflecting her moral conflict.

She maintained kindness toward staff, fans, and animals, owning two dogs named Fortissimo and Pianissimo. Key moments included preventing a fan's suicide through empathetic conversation and song, and surviving a traumatic assault in Guam where attackers destroyed a keepsake from her father.

Her evolution saw her transition from naivety to confidence. She reconciled with Rei, uncovering their cousin relationship. A romance with childhood friend Kazuki culminated in mutual affection. The story concluded with her mother awakening with regained memories, her uncle achieving redemption, and Mónica rising to nationwide fame as a beloved idol singer.