Kawasaki Ki 61 II Kai Hien, 6117
History
The aircraft displayed at the Gifu-Kakamigahara Air and Space Museum is not a Kawasaki Ki-81. It is a Kawasaki Ki-61-II Kai Hien ("Flying Swallow"), one of the rarest surviving Japanese World War II fighters in the world. The Ki-81 was a completely different experimental escort fighter project that never entered production.
The Ki-61 Hien was developed by Kawasaki Heavy Industries during the early years of World War II as the Imperial Japanese Army's Type 3 Fighter. Unlike most Japanese fighters of the period, the Hien used a liquid-cooled inline engine derived from the German Daimler-Benz DB 601. Its streamlined appearance caused Allied pilots to initially mistake it for a German or Italian aircraft, leading to the Allied codename "Tony."
Production of the Hien began in 1942 at Kawasaki's factory in Kakamigahara, Gifu Prefecture. More than 3,000 examples of the Ki-61 and related variants were built there during the war, making the city one of the most important centers of Japanese aircraft manufacturing. The fighter served in New Guinea, the Philippines, Okinawa, and in the defense of the Japanese home islands against B-29 bombing raids.
The aircraft now displayed in the museum is believed to be the only surviving Ki-61 in Japan and one of only a handful left anywhere in the world. After the war, the fighter was captured by U.S. forces and eventually returned to Japanese custody through the Japan Aeronautic Association. Over the decades it appeared at several air exhibitions and museums, including the Chiran Peace Museum for Kamikaze Pilots in Kagoshima Prefecture.
In 2015, the aircraft was transported back to Gifu, the region where it had originally been manufactured. Kawasaki Heavy Industries carried out an extensive restoration project between 2015 and 2016. Rather than restoring the fighter to flying condition, conservators chose to preserve much of its wartime character and structural authenticity. The restoration stripped away old paint layers and repaired corrosion while retaining original materials whenever possible.
When the museum reopened in 2018 after major renovations, the restored Ki-61 became the centerpiece of the aviation gallery. The exhibit was designed to emphasize the aircraft's historical connection to Kakamigahara, where the Hien was once mass-produced during the war. Today the fighter stands as both a technological artifact and a reminder of Japan's wartime aviation industry.