Established in Taisho 12 . Two classes: silver for officers and bronze for NCOs. This award was abolished in 1940, but the NCO class badge was still awarded up until the end of WW2.
Replicas (& fakes) are plentiful.
Scratched into the reverse is this: 'Corporal Takemoto, 58th Graduating Class.' Although I have no information about this soldier, I found out that the 58th Class was the last class that was graduated from the Imperial Army Air Force Academy before the end of WW2. Both a 59th and a 60th Class existed, but neither class completed their study before the war ended. My source also stated that since the 57th and 58th Classes only took a limited number of courses (i.e., they graduated in a shorter time than the earlier classes), upon graduation the soldiers were assigned to be pilot training instructors. The 58th Class entered the academy on December 14, 1943 (1200 students) and was graduated on March 20, 1945 (1176 students). So this badge is a late-war version, dating to 1944-5.