The Yggdrasill Corporation is a massive corporation located in the city of Zawame, providing for just about anything the city needs for living and growth of civilization, from clothing to transportation to even waste disposal, as well as healthcare and education. Its omnipresence in the city's socioeconomic development makes the populace feel that they are living in a castle town rather than a bustling city. Yggdrasill Corporation is one of the two antagonist groups of Kamen Rider Gaim, along with the Overlord Inves.
At some point in the past, the Corporation came to Zawame City in order to redevelop it as part of a project. In the process, they shut down a construction company belonging to Kaito Kumon's father and cut down the Takatsukasa shrine tree along with the entire forest surrounding the city.
The Corporation is also aware of the Helheim Forest's existence and is attempting to harness its power in order to fight against Demushu, the Overlord Inves. While partially successful so far with the Lockseeds, the Sengoku Drivers (and eventually the Genesis Drivers), the Corporation has yet to be "chosen" by the Forest.
- Takatora Kureshima/Kamen Rider Zangetsu - (Leader of the Development branch)
- Mitsuzane Kureshima/Kamen Rider Ryugen - (Former spy and current leader of Research and Development branch)
- Ryoma Sengoku/Kamen Rider Duke - (Scientist)
- Lock Dealer Sid/Kamen Rider Sigurd - (Lockseed Dealer)
- Yoko Minato/Kamen Rider Marika - (Ryoma's assistant)
- Oren Pierre Alfonzo/Kamen Rider Bravo - (defected)
- Hideyasu Jonouchi/Kamen Rider Gridon - (Oren's apprentice and leader of Team Invitto) (defected)
- Kaito Kumon/Kamen Rider Baron - (unwillingly)
- Kurokage Troopers - (Henchmen/Troops)
- DJ Sagara - (Propaganda)
- Akira Kazuraba
- This evil megacorporation was named after the Yggdrasil tree of life that supported the 9 different worlds of Norse mythology.
- Gaim director Ryuta Tasaki noted in an interview with Uchusen magazine that Yggdrasill is a homage to Smart Brain from Kamen Rider 555, one of several references to past Heisei Rider series in the show.