The World Tree YGGDRASIL had countless leaves, but then a giant monster appeared which devoured these leaves, causing them to fall one after the other until only nine were left. These nine leaves were the previous incarnations of the Nine Worlds, particularly Jötunheim. However, the leaf-eating monster continued its advance to the point where it seeks to devour the leaf representing Jötunheim. This was the backstory upon which the players adventured into the world of Jötunheim in order to protect it.
Jötunheim was one of the realms where many players of the humanoid and demi-human races mainly resided in. By entering Jötunheim, players of the heteromorphic races are known to have disadvantages placed on them when faced by non-heteromorphic players.
The world was described to be ridiculously huge, and there were many places within it which were difficult to explore. For instance, there were many areas which required the use of special equipment along with a proper strategy and the determination in order to delve into its hard-to-find dungeons that drop valuable Data Crystals.
Jötunheim is revealed to be a world for where ancient frost dragons are known to reside in. During the course of hunting these said monsters for materials such as their meats, they can then later be served as one of the ingredients for cooking food like marbled steak. It seems apparent that the Great Tomb of Nazarick has at some point in the past, manage to farm or grind for valuable materials from them.
Within Jötunheim, things became more dangerous the further one went from the center of its world. In addition to the wandering monsters, the very terrain itself became a hazard for players to explore.
A developer-sanctioned tournament was held in this world where one could become a World Champion and acquired special powerful equipment awarded as the winner's price for exclusive use with that class. Only one player with the World Champion job class was allowed to exist in Jötunheim. There is also just one guild base in this world that contains 3000 levels of NPC Data Storage which is the highest amount by far available.
- This world has its own particular traits, but they often shared one similarity which is the fact that it is two to three times the size of Tokyo.
- Some guild members of Ainz Ooal Gown had once thought of trying to conquer one of the worlds in YGGDRASIL.
- During an argument with Touch Me, Ulbert Alain Odle wanted Ainz Ooal Gown to farm for frost dragons to fulfill one of their guild member's class-up requirements. "The Ice of the Beginning" item is most presumably in this world based on the fact it is dropped by these dragons.
- In a tournament battle consisting of only the World Champions as participants, the first-place champion of the overall tournament was the Jötunheim's World Champion.
- In Norse mythology Jötunheim is the home to a race of giants known as the jötunn.