The Helheim Forest is the place in Helheim 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.
The Helheim Forest is a semi-alive place, having devoured entire worlds in it's expansion, with it's more recently discovered victim located in a valley. It is controlled by the Overlord Inves.