Karasu, also known as the Mad Bomber, is a major antagonist in the Dark Tournament saga. He is a member of the formidable Team Toguro, the reigning champions of the tournament, and serves as a primary rival to the fox demon Kurama.

Karasu is a demon of the rare Quest class, a classification that grants him the unique and dangerous power to materialize objects out of thin air. Specifically, he creates explosive bombs from his own demon energy. These explosives can vary in size and power, and a particularly fearsome aspect of his ability is that he can make them invisible to the naked eye, making his attacks nearly impossible to predict or defend against. In combat, he is a quick and silent fighter who also enjoys psychological warfare, using mind games to unnerve his opponents.

His appearance is distinctive and contributes to his mysterious aura. Karasu has long, jet-black hair and typically wears a dark, formal-looking outfit. He almost always conceals the lower half of his face with a white, half-face mask, which adds to his aloof and unreadable demeanor. However, the mask serves a deeper purpose beyond aesthetics. When he removes it, it signals a significant shift in his personality and power level. With his mask off, his hair turns blonde, and he reaches the peak of his combat ability, becoming even more ferocious and unstable.

Personality-wise, Karasu presents a cold and calm exterior, showing little interest in those he deems weak. Beneath this composed surface lies a profoundly sadistic and twisted nature. He has a peculiar philosophy centered on destroying the things he likes, claiming that doing so gives him a wonderfully sad feeling. This cruel mindset is most clearly directed at Kurama, for whom he develops a dangerous obsession. He proclaims Kurama to be the fighter he likes best, which, by his own logic, means he is determined to kill him.

Karasu's role in the story is defined by his place on Team Toguro. His background reveals that he once challenged the immensely powerful Toguro brothers alongside his partner, Bui, but was brutally defeated. Rather than kill them, the Toguro brothers forced the pair to become their subordinates. This humiliation fuels Karasu; he swallows his pride to join the team, secretly harboring the long-term goal of one day growing strong enough to kill the Toguro brothers and reclaim his honor. He holds no loyalty to his teammates and would not hesitate to harm them if they got in the way of his attacks.

Throughout the Dark Tournament, Karasu is a key fighter for his team. His most significant relationship is with Kurama, whom he views as a kindred spirit and a worthy target for his obsession. Their long-awaited match in the tournament finals becomes a brutal and psychological battle that pushes Kurama to his absolute limits. In a desperate move, Kurama is forced to consume a parasitic plant to transform into his original, more powerful demon form, Yoko Kurama. Despite Karasu pushing him this far, Kurama ultimately outsmarts him, countering his final, most powerful explosion. Karasu's development is not one of redemption but of a villain whose single-minded obsessions lead to his downfall at the hands of his chosen prey.