Kei, a fourteen-year-old junior high student in Kawasaki’s Kanagawa Prefecture, lives with his abusive father and younger brother Tomo, their mother’s absence marked by a fractured portrait in the virtual realm—a silent testament to lingering grief. His father’s violence leaves physical and emotional scars, with Kei often intercepting attacks meant for Tomo; the bruises materialize as jagged crimson streaks across his virtual avatar’s tattered cape.

In the digital universe "U," Kei becomes the Dragon—a hulling, dragon-themed warrior with razor-tipped claws and a crimson-shrouded guise. His ferocity in battle, fueled by real-world anguish and a resolve to shield Tomo, grants him unmatched power. Aggression masks profound distrust, his towering presence and isolated AI-guarded castle mirroring his emotional barricades. Only Tomo’s angelic avatar, Angel, shares this fortress-sanctuary.

Branded a villain by the vigilante Justices, the Dragon paradoxically inspires adoration among "U’s" younger users, who champion him as their hero—a reflection of Kei’s dual role as both outcast and protector. His guarded walls fracture when Belle, avatar of Suzu, bridges their worlds through persistent empathy. Their bond deepens as Suzu risks exposure by unveiling her identity through song, dismantling his defenses.

Healing unfolds when Suzu confronts Kei’s father in reality, interceding during an attack. This act loosens the grip of trauma: the Dragon’s virtual rage softens, while Kei, no longer hiding behind hair-shrouded eyes, tentatively embraces vulnerability. His journey—from isolation to connection, fury to fragile trust—underscores resilience forged through compassion, a boy and his avatar learning to let others share their burdens.