RKD Group

RKD was a think-tank on Earth. They designed and developed Project HAYABUSA, a powered combat armor similar in many ways to the MJOLNIR pioneered by Doctor Catherine Halsey, though with many differences. After the Human-Covenant war, RKD developed the Mirmillion and Legionnaire variants of the MJOLNIR [GEN2] armor.

Trivia
Since RKD group's Hayabusa Armor is based on that of Ryu Hayabusa of the Ninja Gaiden series of video games, it is possible that RKD is an abbreviation of "Ninja Ryukenden", the original name of that series.

List of appearances

 * Halo 3
 * Halo 5: Guardians
 * Halo Online