The Mitsurugi Agency (御剣機関 Mitsurugi Kikan) is an organization that is responsible for sheltering and studying Drive-Unions.
The Mitsurugi Agency is a massive organization that is wholly responsible for not only sheltering Drive Unions, but also for the study of them. In addition to the study and shelter, the Agency has a formidable military strength, allowing them to subdue even the strongest of Drive Unions, with the sole exception of Ripper, a Phase 0 Drive Union who managed to avoid the organization for 10 years until he met his demise at the hands of Kazuto Kotetsu, a man with an unknown connection to the Agency. By definition, the Agency is technically a private military company (PMC); as well as their own military force, aptly called Sleipnir, the Agency also hires bounty hunters to help capture, or kill, rampaging Unions.
Despite being a PMC, they have strong ties to multiple government agencies and even possess considerable power in the influence of public safety and welfare.
Many years after the Wadatsumi Mass Vanish Incident and the dissolution of the Takamagahara, one of Takamagahara's scientists, Sōichirō Unomaru, became the Mitsurugi Agency's leading director of their Shin-Yokohama's seventh laboratory branch. As well as this, the Agency fully backed him in his desire to continue with the creation of the T-system. As well as Sōichirō, the Agency also recruited Mei Amanohokosaka as a guide through the Wadatsumi area; however, this was in exchange that they kept the body of her father alive despite his lack of soul.
As of at the end of Lost: Memories, Mei is currently the commander of the Sleipnir unit in the Mitsurugi Agency, with Touya and Es-N (who she named Nu) as members under her leadership. Also upon Es's return and Freaks' death, Es rejoined Sleipnir and the Mitsurugi Agency.