"Shigurui" is a historical manga set in early 17th-century Japan during the Edo period, focusing on the brutal and unforgiving world of samurai and their code of honor. The narrative centers on a deadly duel between two swordsmen, Gennosuke Fujiki and Seigen Irako, both disciples of the Kogan-ryu school of swordsmanship under the tutelage of the blind and ruthless master, Kogan Iwamoto. The story begins with the announcement of a tournament sponsored by Lord Tokugawa Tadanaga, where participants are allowed to use real swords, resulting in fatal consequences for many.

Gennosuke Fujiki, a one-armed swordsman, and Seigen Irako, a disgraced former samurai, are the primary combatants. Their rivalry is deeply rooted in personal vendettas, jealousy, and conflicting interpretations of their master's teachings. Gennosuke, despite his physical handicap, embodies discipline and loyalty, while Seigen is driven by ambition, resentment, and a desire to reclaim his lost status. The narrative frequently shifts between the present, depicting the tournament and its immediate aftermath, and the past, exploring the events that led to the characters' current circumstances.

The manga delves into the harsh realities of the samurai lifestyle, emphasizing themes of violence, honor, and the often hypocritical nature of societal expectations. The characters are deeply flawed, and their actions are frequently morally ambiguous. Kogan Iwamoto, the master of the Kogan-ryu school, is portrayed as a tyrannical figure who demands absolute obedience, often pushing his students to their physical and psychological limits. His daughter, Mie Iwamoto, becomes a central figure in the rivalry between Gennosuke and Seigen, further complicating their relationship.

The story also explores the lives of other characters connected to the Kogan-ryu school, including Ushimata Katsuie, a former student who becomes a wandering ronin, and Lady Iku, a noblewoman whose fate becomes intertwined with the main characters. The manga's portrayal of violence is graphic and unflinching, reflecting the brutal nature of the era and the samurai code. The narrative builds toward a climactic confrontation between Gennosuke and Seigen, culminating in a duel that is as much a battle of ideologies as it is a physical fight.

"Shigurui" is noted for its meticulous attention to historical detail, particularly in its depiction of samurai culture, sword techniques, and the socio-political climate of the Edo period. The story is a grim exploration of human ambition, the cost of loyalty, and the destructive consequences of obsession.