Kaito Daimon, a high school student renowned for his puzzle-solving prowess, channels his trauma over his parents’ lethal puzzle-related demise into a relentless drive to prevent puzzles from causing harm. His disheveled brown hair, swept into a short ponytail, frames layered dark brown eyes, while his casual ensemble—a red unzipped vest over a sleeveless black shirt and green baggy pants—contrasts with distinctive accessories: sunglasses perched in his hair and the Orpheus Armband clasped to his right arm. This enigmatic device amplifies his cognitive speed under duress at the cost of temporary exhaustion, later unleashing catastrophic visions when overused.

Brash and rule-averse, Kaito’s obsession with puzzles initially overshadows consequences, yet his hardened exterior softens through alliances and conflicts. He shields childhood friend Nonoha Itou from danger despite mocking her culinary skills, and navigates complex bonds with figures like Rook Banjou Crossfield—a childhood companion turned rival then ally—whose volatile Orpheus Armband-fueled behavior tests their camaraderie. Mentor Jin Makata anchors Kaito’s quest to reclaim erased memories and dismantle manipulative schemes, while rivalry with Gammon Sakanoue, who joins the antagonistic P.O.G. to outmatch him, fuels Kaito’s resolve to prove puzzles inspire joy, not destruction.

Initially hostile toward Freecell over past grievances, Kaito forges grudging respect with him as they unite against the Orpheus Order. The armband’s evolution mirrors his growth: once a crutch for solving puzzles, it later inundates him with apocalyptic foresight, culminating in its destruction. Freed from its physical influence, Kaito retains sharpened abilities, symbolizing his self-reliance. Across escalating crises, he thwarts the Orpheus Order’s global threats, mends Jin’s fractured memories, and collaborates with former foes like Rook and Freecell to neutralize the cataclysmic "Divine Puzzle."

His name, a playful nod to "mondai kaitou" ("problem solver"), underscores his identity. The armband’s activation ignites a crimson glow in his right eye, marking heightened focus. Despite enduring manipulation and loss, Kaito steadfastly champions puzzles as vessels of their creators’ true intent, resolving clashes through empathy and intellect over brute force.