Valhalla is once again under attack by the Imperium and the game starts off with them attacking Amy's home village. Akira and Jin set off to find the stones that were used by the "Legendary Messiah" to seal away an ancient demon. This demon has now been freed and is leading the Imperiums Forces after the fall of its former rulers.

A real time strategy game, each demon has only two attacks, a physical based strike, or a magical based skill. Akira and Jin ride their demon partners Rand and Gale on the field and must summon other demons. Then the player must move them and command them to attack in order to fight enemies. The game lacks the ability to converse with enemy demons, instead a demons soul can be acquired after defeating them, which recruits the demon onto their team. A demon must be placed on the soul in order to acquire it, with demons of the same element being the most compatible while the element they are strong/weak to having the lowest chance of succeeding. Souls disappear over time.

The number of demons Akira or Jin can summon is based on the points they have and the demon's call cost. The demons call cost is subtracted from Akira and Jin's total pool, the cost of which is normally 15 points. There are special floating orbs on the field which gives Jin and Akira an extra 15 points so they can summon more demons, including ones that are higher leveled than them. The points revert to normal after the battle. Jin and Akira are the only characters who level up during the game, and like previous games their demons will evolve at certain points of the story. The fusion system returns.

Ten of a single demon can be traded for a more powerful demon at certain towns.