The HsF (Hard science Fighter) is a series of supersonic fighters developed by Academy City. The only iteration seen in the series so far has been the HsF-00, deployed by Academy City during World War III. Based on the HsB-02 supersonic stealth bomber, the HsF-00 is an 80-meter fighter that can fly at 7000 km/h. Thanks to its superior speed, weaponry and technology, just ten HsF-00 supported by a small number of smaller unidentified special mid-air refuelling crafts were enough for Academy City to maintain air superiority over the Sea of Japan and easily defeat the Russian air forces sent to attack them.