Onimusha: Warlords is the first game of the Onimusha series.

The game features samurai Samanosuke Akechi, modeled after actor Takeshi Kaneshiro, determined to save Princess Yuki of the Saito clan and defeat Nobunaga, resurrected after signing a pact with demons. The game also features Kaede, an expert female ninja who provides Samanosuke with information. Kaede was originally sent to assassinate Samanosuke by the Iga clan of ninja, but had a change of heart and develops trust and deep feelings of love (as shown in Onimusha Blade Warriors) for the samurai and agrees to join him as his confidant. Samansosuke travels throughout all of Inabayama Castle where he searches for clues of Princess Yuki's whereabouts, finds special weapons, and solves various puzzles.