Aura Kingdom, also known as Fantasy Frontier Online (Chinese: 幻想神域) in Taiwan and Hong Kong and Innocent World in Japan, is a massively multiplayer online role-playing game made by the Taiwanese game developer X-Legend.

[4] Players take on the role of Envoys of Gaia, who they are tasked with the mission to save Azuria, the fantasy world of Aura Kingdom, from Darkness.

[5] Players can choose sixteen classes to play from: Guardian, Ravager, Duelist, Gunslinger, Grenadier, Bard, Wizard, Sorcerer, Brawler, Ranger, Ronin, Reaper, Crusader, Ninja, Lancer, and Performer.

Players can then choose one of the four starting pet Eidolons, with the opportunity of recruiting more as the game progresses.

These spirits are known as ‘Eidolons’ that retain memories of players' accomplishments, such as boss kills, and can be conversed with.