Embark on a mythical journey in the ancient city of "Oos," surrounded by celestial waters and mystical clouds. In this realm, four major tribes worship the deity of Oceanian waters, fostering cultural prosperity and harmony. Adventurers unite to form guilds, defending their homeland against powerful dragons and other creatures. Players choose professions ranging from mages, swordsmen, archers to engineers, assassins, and more, venturing outside the city for lucrative rewards.

Every year, Oos holds competitions to select the strongest adventurers in each profession, appointing them as heroic champions to safeguard the city from formidable threats. However, a sudden celestial disturbance leads to the emergence of a powerful demonic entity, plunging the world into chaos. As the light dims, adventurers gear up for an epic battle to vanquish the malevolent forces threatening their homeland.