Kohei Makino begins as a high school peer of Mana Nagase, reluctantly stepping into the role of her manager at Hoshimi Production when she leverages their classroom proximity to recruit him. Plagued by a chronic inability to decline requests, he dedicates himself to facilitating Mana’s meteoric ascent as a solo idol, compensating for his lack of formal training with unwavering diligence. Her sudden death in a traffic accident—en route to the Venus Grand Prix finals—leaves him adrift, yet he persists at Hoshimi, shepherding a new wave of talents: Kotono Nagase, Mana’s younger sister, and Sakura Kawasaki, a vocalist eerily mirroring Mana’s timbre.

Mana’s ghost lingers as a spectral companion, visible solely to Kohei and Mei Hayasaka, a later addition to the agency. Through whispered advice and ethereal camaraderie, their bond deepens posthumously, with unspoken romantic tensions crystallizing in a parting kiss as Mana finally transcends to the afterlife—a catharsis that untangles Kohei’s grief and propels him toward nurturing his proteges.

In the game narrative, he functions as a player avatar, anonymized as “Manager,” balancing dual responsibilities for idol units Moon Tempest and Sunny Peace. Critical revelations reshape his mission: uncovering Sakura’s receipt of Mana’s transplanted heart amplifies his resolve to help her and Kotono carve distinct identities beyond their ties to the past. His arc traces a shift from spectral fixation to forward momentum, channeling loss into mentorship as he steers fledgling idols toward futures unshackled from legacy’s shadow.