Mika Kagehira attends Yumenosaki Academy as a member of the idol unit Valkyrie under COSMIC PRODUCTION. Abandoned in childhood, he grew up in a Kansai orphanage where negative attention to his heterochromia—a light golden right eye and aqua left eye—bred a complex and fear of abandonment. This led to excessive compliance, expressed through caring for younger children and avoiding complaints to prevent rejection. He first encountered Shu Itsuki after fleeing the orphanage, mistaking Shu's elaborate attire for a divine being; the meeting seared into his memory. Upon later seeing Shu on television, Mika enrolled at Yumenosaki solely to reunite with him. Initially disinterested in idol work, he accepted Shu's invitation to join Valkyrie as a backup dancer, eventually becoming a full member alongside Nazuna Nito. Valkyrie's early concept centered on marionette theater, Shu as the puppeteer. Mika embraced the "doll" role, finding purpose in executing Shu's vision. Intensely loyal, Mika struggles with emotional regulation, frequently overwhelmed by jealousy or insecurity. He resented Nazuna for perceived favoritism from Shu. After Nazuna left Valkyrie, Mika branded him a "betrayer," though privately retaining affection. Following Valkyrie's collapse during The War, a listless Shu relied on Mika's physical and financial support. Mika took multiple part-time jobs to sustain the unit while also sending earnings to his adoptive family in Kansai. This grueling workload caused chronic fatigue, weight loss, and fainting spells, alarming his peers. His development pivoted during Valkyrie's revival. After a temporary separation from Shu, Mika returned to his hometown and discovered children there idolized him as an attainable role model, unlike the distant Shu. This inspired his dream to become a "light" for marginalized youth through his art. While still viewing Shu as a mentor, he began forging his own artistic identity, creating performances blending melancholy with warmth. Shu acknowledged this shift, urging Mika to express his voice independently. Mika retains traits like an airheaded demeanor, Kansai dialect, and fondness for amateurish sweets or repaired discarded items. He is night-blind and possesses high pain tolerance, often injuring himself unnoticed while sewing. His appearance features crow-like black hair and a slender build, with habitually untidy school attire contrasting Valkyrie's elaborate Victorian-inspired stage costumes adorned with rose accents. His relationship with Shu evolved from dependency into mutual partnership. Shu ceased treating him as a doll but maintained rituals like physical "maintenance" checkups, symbolizing their enduring bond. Both now regard each other as irreplaceable artistic collaborators, with Mika declaring he would follow Shu "into the pits of hell."