|This article is about a/an location in Kamen Rider Gaim.|
The Helheim Forest (ヘルヘイムの森 Heruheimu no Mori), shortened to just "Helheim", is the place which the Inves call home and where the Lockseeds are grown in abundance. Inves from the Helheim Forest are more powerful than the ones that are summoned by the Beat Riders. In order to enter this forest, one must have a Lock Vehicle, which can transport an Armored Rider at a sufficient speed, or find a random crack. The Yggdrasill Corporation somewhat also has a portal to the Helheim Forest in their base, which only someone who is from Yggdrasill knows about. It is revealed later that Helheim was actually on another planet, the Femushinmu Planet.
The Helheim Forest is a semi-alive place, having devoured entire worlds in its expansion, with its more recently discovered victim located in a valley. It is controlled by the Over Lord Inves, who control the plants and the very environment of Helheim itself. However, DJ Sagara is the very spirit of Helheim itself, making him the true ruler of the forest.
In the penultimate episode, the Forest was moved to a planet near the edge of the universe to prevent Helheim from snuffing out life on Earth.
Kamen Rider Zi-O
Due to a temporal disruption caused by Another Gaim, the Helheim Forest's invasion to Earth is stalled. Another Gaim himself has the power to open cracks to send people to an artificial facsimile of the Forest. This Helheim Forest has enough safe and edible foods for Kaito and his teammates to survive for at least 5 years.
The name Helheim is based in a location in the Norse mythology. Helheim is known as the realm of death and one of the nine worlds of the Yggdrasil, the tree of life.