Gonzaemon Ushimata is a central figure in the Kogan-ryu dojo, known as its main instructor and the most senior disciple. He is a man of immense physical stature and supernatural strength, which earned him the nickname the Tiger of the Kogan-ryu, often paired with his rival Gennosuke Fujiki, who was known as the Dragon. As a boy named Gonzaburo, his incredible power made him an outcast; he was shunned as a wild boar because no adult could safely take a practice sword from him. His talent was recognized by an instructor who recommended him to the Kogan-ryu, and upon his initiation, he demonstrated his formidable constitution by wrestling evenly with a senior student, Ibuki Hanshinken.

Ushimata’s defining characteristic is his absolute, terrifying loyalty to his master, Iwamoto Kogan. This devotion transcends all reason and social convention, manifesting as a profound and unsettling madness. In one striking instance, after Kogan discovered an affair and retaliated by mutilating his mistress, Iku, Ushimata ate the severed piece of flesh without hesitation, an act that illustrates his complete identification with his master's will and his function as a living embodiment of Kogan’s punishment. His obedience is so extreme that he once stood perfectly still while Kogan, in a blind rage, struck him repeatedly in the mouth, destroying most of his teeth. Ushimata never voiced a word of resentment for this or any other ordeal. This blind devotion was further demonstrated when his master left the dojo for three days, commanding him to train; Ushimata practiced without stopping, refusing to eat, sleep, or rest until Kogan returned.

Despite mastering Kogan-ryu swordsmanship through a combination of innate strength and fanatical dedication, Ushimata was prevented from becoming the school’s successor for a specific and humiliating reason: he was a eunuch. This physical condition symbolically distanced him from the lineage and legacy Kogan wished to cultivate, particularly in contrast to rivals like Seigen Irako who were brought into the family to produce strong offspring. His backstory also involves a childhood sweetheart he left behind; though he ultimately could not bring himself to harm her, his lingering attachment was seen as a weakness by his master.

Within the narrative, Ushimata plays the role of the dojo’s ultimate enforcer and a relentless instrument of its wrath. He regularly traveled to other dojos in the summer to challenge them, serving as a brutal reminder of the Kogan-ryu’s fearsome power. His most significant and horrifying role comes during the chaotic duel between his comrades and the vengeful Seigen Irako. Acting as a one-man army, Ushimata abandoned the samurai code of honor, which dictated rules for duels and reinforcements, and launched a frenzied, indiscriminate massacre. Wielding two spears, he slaughtered countless samurai, regardless of age or involvement, an atrocity so severe that the lord hosting the duel was forced to take responsibility and commit seppuku. In this state of pure, unadulterated rage, he became a monstrous, unstoppable force that broke every moral and ethical code of the warrior class.

His key relationships are defined by this unwavering loyalty. His bond with his master, Kogan, is one of utter subservience, yet it is a twisted partnership where his own humanity is sacrificed. His rivalry with Gennosuke Fujiki is central to the dojo’s dynamic, the two being the tiger and dragon of the school, though their fates are intertwined in a spiral of violence. In contrast, he harbors a deep and violent hatred for Seigen Irako, viewing him as a traitor whose actions would ultimately precipitate the downfall of the Kogan-ryu.

The character undergoes a development from a silent, stoic enforcer to a completely unhinged engine of destruction. His anguished past and his master’s abuses, which he internalized rather than resisted, all culminate in his final explosive rampage. Even after being mortally wounded by Seigen Irako’s technique, his hatred and purpose allowed him to continue functioning, breaking into a rival swordsman’s mansion to collapse and die only after his vengeance was complete, a testament to his terrifying persistence. As a fighter, Ushimata’s notable abilities are his preternatural strength and endurance. He is known to wield an immensely large wooden sword, a suburito, with effortless ease. In his final battle, he demonstrated proficiency with dual spears, cutting down all who stood in his path until his body simply could no longer carry his will.