In the world of Junovald death is not a natural process. After dying all living things come back as monsters, and the monsters will revive eternally. Only the power of a Sealer can put a soul to rest. Accompanying Sealers are Blades, the most skilled warriors in the world. After a new weapon is delivered to a remote kingdom to deal with their monster problem the king and his eldest son are slain, and the weapon stolen. A Sealer, Aisha, takes the soul of the dying Blade, Nine, into her body, allowing him a second chance for vengeance.
Nine and Aisha travel through many linear levels as they cross the land, trailing Nine's killer. Items, accessories, and spells are found in treasure chests along the way. Because the two protagonists share a single body they also share stats and an HP bar, but spells must be equipped on either Nine or Aisha. In combat multiple body parts of monsters can be targeted with physical attacks, and if the parts are attacked in the correct order will create a combo chain. Hits that are chained will result in more "stamps" being applied to a body part, and when magic is cast it will hit each enemy for every stamp on them. Once an enemy has fallen it can either be poached for MP by Nine, or killed for good by Aisha.
As revealed in an interview with Siliconera, Haru Akenaga, president of NIS America, did not want to publish Last Rebellion. After receiving a copy of the game told the company's PR manager not to push the title. He apologized for having to release the game, and has promised to never release another game of that quality.