The ACTF in Warrior Guyver
The ACTF in Son of Mine ('verse)
Formed from elements of the US Army that have been confirmed to be free from genetic tampering by Chronos, the ACTF first appeared at the end of the first story in the series, but did not play a truly prominant role until the third.
When Ryan Crouger went to Los Angeles to investigate the sense that he, Agito, and Sho had been getting - the sense that another Guyver was over there, the ACTF made their rirst true appearance. Ryan's first meeting with Sean Barker, the ACTF's only allied Guyver at that point in time, lead to him finding out about the other allies their side had in the battle against Chronos.
Joining up with them at Sean's insistance, Ryan quickly found himself on the wrong end of the older Guyver's suspitions once the matter of his hybrid status had been brought up. With all the time and effort that they had put into fighting the company and its legions of Zoanoids, it is rather understandable that they would not be so quick to trust someone who seemed to clearly display signs of Chronos' genetic tampering. Still, Atkins gave Ryan a chance, since he was a Guyver and he had acted trustworthy up to that point.