Movie
Description
Kōji Mihama spent his childhood in Tokyo with his mother, Natsuko Mihama, and his house-husband father, Takeyuki Mihama. Takeyuki taught him guitar, singing, and cooking, fostering a cheerful upbringing. After Takeyuki's death, Kōji's personality shifted dramatically towards quietness and gloom; he rarely smiled again. He enrolled at Edel Rose Academy despite his mother's objections about songwriting. At age 13 in his first year, classmates mocked his music for sounding childish until Hiro Hayami recognized his talent and requested a collaborative song.

Two years later, during his third year of middle school, Kōji formed a unit with Hiro for their idol debut. He composed "Pride" for their joint performance, but Hiro claimed sole authorship under supervisor Jin Norizuki's advice. Feeling betrayed, Kōji confronted Hiro and quit both the unit and Edel Rose, entering a depressive slump. His creative spark reignited after encountering Naru Ayase, who sought one of his songs for her Prism Show. Though initially refusing, her subsequent apology and understanding of artistic value inspired him to write her debut song "Heart Various Colored Dream."

Kōji later witnessed Ito Suzuno's intense Prism Live performance, leading to their acquaintance. When Hiro commissioned a song from Ito, Kōji attempted to dissuade her, fearing Hiro would plagiarize again. Misinterpreting his warning as dismissiveness, Ito rejected his advice. To protect her work, Kōji gave "Pride" to Hiro instead, enabling Hiro's debut under false authorship. During the Try Groovin' Session, Kōji rearranged Ito's original song intended for Hiro into a love confession. After Naru revealed this intent, Ito pursued Kōji, who reciprocated her feelings with a kiss, initiating their relationship.

Their romance faced familial opposition due to unresolved conflict between the Mihama and Suzuno families, stemming from a car accident involving Kōji's father and Ito's father. Learning this history, Ito temporarily ended their relationship. Kōji confronted his mother about moving forward and persuaded Ito to reconcile during a meeting facilitated by Otoha at a bathhouse. Both families eventually resolved their dispute.

Despite lingering resentment toward Hiro, Kōji composed "Freedom" for Kazuki Nishina's rematch against Hiro. The song's lyrics echoed Hiro's past words to Kōji. After Hiro publicly apologized for claiming "Pride," Kazuki persuaded Hiro that Kōji welcomed his return. Kōji then proposed rebuilding their relationship, leading to the formation of Over The Rainbow with Hiro and Kazuki.

In subsequent years, Kōji regained his original lively demeanor. His career expanded beyond Over The Rainbow to include hosting a TV cooking show and extensive composing, with overseas offers flooding in due to his "demonic-level" songwriting charm. He joined the band Cross Road with Ito and her brother Yuu Suzuno. To help repay Edel Rose's debt, he accepted an offer to compose a Hollywood movie soundtrack in America. He remained responsible for designing Over The Rainbow's performance costumes and wore his father's dog tag alongside the unit's purple wristband.

Physically, Kōji is tall with chartreuse eyes and ash brown or dim gray shoulder-length hair, often tied in a ponytail. He is typically kind and soft-spoken but displays unpredictable or mysterious behavior, always with good intentions. Hiro notes his easily provoked anger, while others observe his occasional strictness and unintentionally intimidating demeanor. His passions for music and cooking persist, with compositions like "Sweet time Cooking magic ~I'm So Hungry~" originating from childhood kitchen sessions with his father.