RKD Group

RKD is a think-tank on Earth.

They built and designed a MJOLNIR Mk.VI Powered Assault Armor variant for Project HAYABUSA called the "Hayabusa".

Trivia
RKD's Hayabusa Armor is based on that of Ryu Hayabusa of the Ninja Gaiden series of video games. It is then likely that RKD is an abbreviation of "Ninja Ryukenden", the original name of that series.