Kiyomori, also known as Henry, is the primary antagonist and the flamboyantly violent leader of the red-clad Heike clan. His background is rooted in a desire to resurrect the fortunes of his clan, modeled after the historical Taira clan from the Genpei War, as he leads his gang from town to town in search of gold. Upon discovering a potential fortune in a remote Nevada town, he establishes his base there by murdering the mayor, igniting a bloody rivalry with the opposing white Genji clan. His most defining characteristic is his obsessive desire to be called Henry, a name he adopts from Shakespeare's Henry VI, because in the Bard's stories of the Wars of the Roses, the red faction ultimately triumphs. This delusion of grandeur fuels his cruelty and his constant, almost mantra-like declaration that "this time, the Reds win".

Personality-wise, Kiyomori is a study in contradictions: he is loud and tyrannical towards his underlings, yet fundamentally a coward who lacks personal courage in a fight. He frequently uses his own men as human shields to protect himself from gunfire, demonstrating a complete disregard for their lives. His motivations are purely selfish, driven by a lust for gold and power, and he shows no hesitation in committing heinous acts to achieve his goals. He murders the Genji's beloved Shizuka's husband Akira in cold blood and assaults her, an act that solidifies him as a ruthless and unforgivable villain within the story's world.

In the narrative, Kiyomori serves as the direct counterpart to the honorable but equally fierce Genji leader, Yoshitsune, setting the stage for the town's central conflict. His role is to be the chaotic and brutal force that the nameless Gunman must outwit and destroy. His key relationships are defined by opposition. He is locked in a violent stalemate with his rival Yoshitsune, whom he eventually faces in a climactic gun battle. He also has a purely transactional relationship with the town's opportunistic sheriff, whom he bullies and abuses. Throughout the film, Kiyomori exhibits little to no positive character development, remaining a force of selfish, bombastic cruelty from his introduction to his demise. His end comes during the final confrontation with the Genji and the Gunman, where his obsession with his Shakespearean identity and his cowardice ultimately lead to his downfall at the hands of a more skilled and honorable opponent. Despite his cowardice, Kiyomori is notably deadly when attacking from a position of power, capable of personally massacring his enemies and wielding heavy weaponry like a Gatling gun to devastating effect.