The game is loosely staged in Japan’s Edo period. A new shogun has unified Japan after years of war. However, a mysterious warlord known as Kage-sama has emerged, jeopardizing the country’s stability. The shogun assigns Oshiro Mugen, a samurai in his service, to find out Kage-sama’s identity, as well as eliminate him and his allies. During his missions, Mugen meets and recruits four agents specializing in infiltration and assassination: Hayato, a grim ninja from Iga; Yuki, a clever, inquisitive young runaway and thief; Aiko, a kunoichi from Shinano and Mugen’s paramour; and Takuma, a sharpshooter and genius gunsmith and alchemist.