Which aircraft had the shortest operational life?
Japanese Ki-100 made its combat debut on the night of 9 March 1945. The last loss of a Ki-100 occurred on 14 August 1945, a day before the surrender of Japan. Hence the  interceptor has been in the service for 158 days, or 5 months 5 days, with 396 units produced.

Looks like nothing bad can be said about this interceptor. It has been recently developed, without major flaws, and, as such, was obviously superior to the older models. It was between the first interceptors to feature the factory-installed armor and self-sealing fuel tanks, and some think it was the best interceptor used by the Army during entire war. But, with the end of the war, it was no longer required.