The experimental tactical fighter nicknamed "Sigrdrifa" is known to be modified from FAS-24 of the Moon Frontier Defense Force, and its model is unknown. It is speculated to be "YFAS-29". She is a new generation of manned fighter developed by human beings on earth to cope with the unknown threat civilization in the Milky Way, equipped with the third generation inertial buffer, which makes it have the maneuverability to withstand the horror of 40 G forces. Because it is expensive, it cannot be mass-produced, and it was snowed after quelling the rebellion of the border immigrant planet.At present, only a few ace pilots of the interstellar migration fleet are equipped with this aircraft.