"Sword for Truth" is a 1990 anime film set in feudal Japan, blending historical elements with supernatural themes. The narrative centers on Shuranosuke Sakaki, a masterless samurai (ronin) who wields a cursed sword known as the Tenrou. This blade, forged from a meteorite, grants its wielder immense power but at the cost of their sanity and humanity. Shuranosuke is a stoic and skilled warrior, driven by a personal code of honor, yet haunted by the sword's dark influence.

The story begins with Shuranosuke being hired by a wealthy merchant to rescue his daughter, Sayaka, who has been kidnapped by a group of bandits. As Shuranosuke embarks on his mission, it becomes clear that the bandits are not ordinary criminals but are led by a mysterious and powerful figure named Genbu, who seeks to harness the Tenrou's power for his own nefarious purposes. Genbu's motives are tied to a larger conspiracy involving the sword's origins and its connection to a celestial event that could bring about chaos and destruction.

Throughout the film, Shuranosuke faces numerous adversaries, including supernatural beings and skilled swordsmen, all while struggling to maintain control over the Tenrou's corrupting influence. His journey is marked by intense battles, moral dilemmas, and moments of introspection as he grapples with the sword's curse and his own inner demons. Sayaka, the kidnapped daughter, becomes a key figure in the story, not only as a damsel in distress but also as a symbol of purity and hope that contrasts with the darkness surrounding Shuranosuke.

The climax of the story sees Shuranosuke confronting Genbu in a final, epic battle. The resolution of their conflict hinges on Shuranosuke's ability to overcome the Tenrou's curse and assert his humanity, even as the sword's power threatens to consume him. The film concludes with a poignant exploration of themes such as redemption, the cost of power, and the struggle between light and darkness within the human soul. The characters' fates are left open to interpretation, emphasizing the cyclical nature of the sword's curse and the enduring impact of Shuranosuke's choices.