The Yokosuka K5Y was a two-seat unequal-span biplane trainer (Allied reporting name: "Willow") that served in the Imperial Japanese Navy during World War II. Indonesian People's Security Force (the precursor of Indonesian Air Force) operated derelict aircraft against Dutch colonial rule. On July 29 1947, Indonesia using 2 units of Yokosuka K5Y (Called "Cureng/Churen" by Indonesian fighters) with one "Guntei Bomber" (Mitsubishi Ki-51 from Maguwo Air Force Base, Yogyakarta for bombing Dutch strategic positions in Ambarawa, Salatiga and Semarang. On its original plan, Nakajima Ki-43 "Hayabusa" also planned to be involved too in this operation, but cancelled as the aircraft suffers technical difficulties. It is currently on display at Jakarta.