Yggdrasill Corporation

The Yggdrasill Corporation (ユグドラシルコーポレーション) 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.

It's named after the tree of life that supported the nine different worlds of Norse mythology.

History
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.

On a side note, the Corporation is also aware of the Helheim Forest's existence and is attempting to harness its power in order to fight against the Over Lord 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.

Members

 * Takatora Kureshima (Kamen Rider Zangetsu/Zangetsu Shin) (former leader of Research and Development branch) (betrayed and defected. Temporary allied with Rosyuo before knowing of their invasion on Earth)
 * Mitsuzane Kureshima (Kamen Rider Ryugen) (Takatora's younger brother, initial member/third leader of Team Gaim, leader of Special Ops, former spy and current leader of Research and Development branch, secretly working together with Sid then Redyue)
 * Ryoma Sengoku (Kamen Rider Duke) (creator of the Rider belts)
 * Lock Dealer Sid (Kamen Rider Sigurd) (Lockseed dealer) (defected, secretly worked together with Mitsuzane) (deceased)
 * Yoko Minato (Kamen Rider Marika) (Ryoma's loyal servant)
 * Oren Pierre Alfonzo (Kamen Rider Bravo) (owner of Charmant and enforcer) (defected)
 * Hideyasu Jonouchi (Kamen Rider Gridon) (Oren's apprentice and leader of Team Invitto) (defected)
 * Kaito Kumon (Kamen Rider Baron) (Acts as their scout, actually using them to gain more power)
 * Kurokage Troopers (Henchmen/Troops)
 * DJ Sagara (Propaganda)
 * Akira Kazuraba

Basis
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.