TV-Series
Description
Kojirō Sasaki is a legendary swordsman who originally lived during the Edo period, approximately four hundred years before the main events of the story. He is best known in history as the rival of the famed swordsman Miyamoto Musashi, having faced him in the infamous duel on Ganryūjima, where Sasaki was ultimately defeated and killed. In the narrative, he is resurrected in the modern day by a subordinate acting on the orders of the antagonist, returning to the world of the living as a revived being. His body has been preserved by the supernatural power of his blade, and after his revival, his eyes take on a distinctive red hue that marks his unnatural state.

Physically, Sasaki is depicted as a tall young man with an attractive, well-proportioned face and a flamboyant sense of style. He wears his long black hair tied high on his head in a ponytail and is usually dressed in a blue kimono topped with an ornate, colorful haori. His appearance is deliberately striking, and he carries himself with an air of supreme self-confidence.

Sasaki's personality is layered and often contradictory, which makes him one of the more dynamic figures in the story. He is highly narcissistic and openly refers to himself in grandiose terms. He is also an unabashed womanizer, showing a strong and often comical attraction to women, and he relishes the attention he receives from them due to his looks. Beneath this vanity, however, he possesses a genuinely opportunistic and duplicitous nature. He is pragmatic to the point of being fickle, frequently shifting his allegiances based on which side appears most advantageous at any given moment. This unpredictability means he can act as a formidable enemy one moment and a reluctant ally the next. Despite his cunning, he also has a more earnest side; he takes genuine pride in his swordsmanship and has a deep-seated desire to prove his superiority.

The primary motivation driving Sasaki is his obsession with Miyamoto Musashi. Their centuries-old rivalry is the defining conflict of his existence. He is consumed by a desire to settle the score and prove that he is the greater swordsman. This fixation often puts him at odds with the main protagonist, whom he sees both as a connection to Musashi and as a new rival to test his skills against. His actions are frequently geared toward proving his strength and achieving the recognition he feels he deserves as the greatest swordsman.

In the story, Sasaki serves a fluid role that evolves over time. He is initially reintroduced as an enemy, a powerful obstacle resurrected to serve the villain's purposes. However, his independent and self-serving nature means he refuses to be a mere pawn. He quickly breaks away from direct control and begins acting on his own whims. This leads him to a complicated relationship with the main characters, where he oscillates between being a dangerous antagonist and a situational ally. He often finds himself fighting alongside the heroes against common enemies, though his loyalty is always conditional and for his own benefit. His presence adds a significant element of unpredictability to the plot.

His key relationship is with Miyamoto Musashi. Their dynamic is one of bitter rivalry mixed with a grudging mutual respect for each other's abilities. Sasaki is both dismissive of the older, aged version of Musashi and enraged by the memory of his defeat. Their interactions are charged with tension, and they frequently compete or come to blows. Another important dynamic is with the young protagonist. Sasaki views him initially as a target but later as a tool or a rival whose growth he observes and sometimes tests. He also interacts with other swordsmen and figures from history, forming loose alliances or rivalries based on circumstance.

Sasaki's abilities as a swordsman are exceptional. He is described by Musashi as a once-in-a-century genius. His primary weapon is a uniquely long sword known as the Monohoshizao, or Clothes Hanger Pole. This sword has a supernatural property that allows its blade to extend at Sasaki's command, greatly expanding his reach and allowing him to strike from unexpected distances. In addition to this, the weapon possesses the power to cut through space and time, which is how he was resurrected. Sasaki's skill with this blade is such that he can cut through solid rock, massive structures, and multiple opponents with a single stroke. His most famous technique is the Tsubame Gaeshi, or Swallow Reversal, a powerful and intricate sword stroke capable of striking an opponent from a blind angle. Even after his revival, his combat prowess is sufficient to challenge and push back seasoned warriors, though he is ultimately defeated by the protagonist after the latter gains new power. Throughout the story, Sasaki's journey sees him transition from a pure antagonist to a more ambiguous figure, occasionally contributing to the heroes' cause while never fully abandoning his selfish goals. His development is not about redemption but about the gradual, reluctant formation of bonds that complicate his simple desire for personal glory.