As the Army's main fighter from the middle of the war onwards, the Hien appeared with a water-cooled engine. The performance-enhanced type with the engine replaced by the higher-powered Hur 140 was the Type 2 Kai, which appeared in 1944. Compared to the previous Type I, its speed, climbing ability and high-altitude performance were improved, and it fought as a new force in the B-29 interceptor war, making use of its high-altitude performance. Overall length 127 mm, width 167 mm, with a choice of markings from two types of fighter squadrons and one type belonging to the 56th squadron.