Hideo was an Intel Team agent for the private military company Militaires Sans Frontières.

At some point, the Militaires Sans Frontières managed to recruit Hideo into the group, with his joining the Intel Team, one of five divisions within the private military company dedicated to finding any strategic elements in an assigned area as well as supplying information for MSF. He eventually became an important asset to MSF, and Kazuhira Miller asserted that "calling him a Critical VIP would be a massive understatement."

At some point in his career, he was assigned to an undercover position at a U.S. prison camp in Cuba. Near the end of this assignment, Hideo recovered a cassette tape containing vital intelligence, and requested that he be extracted from his post, proving his identity by sending Big Boss his signature J.F. Rey Eyewear JF1142 col 2924 (Ocean/Turquoise) eyeglasses.

Despite this, on December 7, 1974, at 05:31, he was compromised, and was forced to hijack an enemy Jeep and signal for a new rendevous point. When MSF went to extract him, he attempted to hail their Hind and request extraction due to being ambushed. However, they weren't able to help due to static interference blocking out the call. As a result, Hideo had to use a flare to signal the chopper his location. Big Boss arrived and provided fire support from an MSF Hind D, escorting him to the base's helipad for extraction. However, his Jeep was disabled by enemy forces, forcing Big Boss to intervene directly to save the agent. After defeating the pursuing enemy forces and disabling a Blackhawk chopper that was pursuing the extraction vehicle, Big Boss and Hideo managed to escape with the tape.