Biscus Colin, a cunning thief from a magical realm, specializes in pilfering enchanted artifacts—most notably a pair of mystical briefcases—sparking a clash with the protagonist. During one botched theft, his startled reaction triggers an unintended spell, hurling both himself and his adversary into the human world and scattering one briefcase into oblivion. Stranded, he forges a partnership with Ochiba, a shrewd ramen stand owner whose greed and moral flexibility mirror his own.

Driven by a hunger for wealth and endless bowls of ramen, Biscus devises schemes to exploit stolen magic for swindling unsuspecting victims. Yet his ambitions are perpetually undermined by comical ineptitude, chaotic mishaps, or meddling outsiders, rendering his antics more farcical than formidable. A surly grey cat, echoing his abrasive personality, shadows his every misstep.

Initially a self-centered opportunist, Biscus begrudgingly collaborates with the protagonist when survival demands it. Gradually, encounters with unexpected human compassion erode his mercenary instincts, steering him toward redemption. By the series’ end, stripped of magic and fully mortal, he renounces his destructive past. Vowing to chart a nobler path, he embarks on a journey of self-discovery alongside his feline accomplice, marking a tentative yet earnest rebirth.