Set against the backdrop of the Onin Wars during Japan's Muromachi period, the story follows five formidable mercenaries who offer their skills to the highest bidder. Onimaru leads the group, Bo specializes in demolitions, Saru moves with the nimbleness of a monkey, Osamu serves as a composed strategist, and Kiri is a seductive swordswoman. Their ranks grow when Onimaru rescues Princess Aya, who immediately falls in love with him and refuses to leave.