Oil Pressure Gage, Japanese WWII-era, Yokohama

Based upon our research of the Kanji characters on the face of this instrument, this appears to be a Japanese Oil Pressure Gage, made by Yokohama, and is believed to be WWII-vintage.  Also believed to have been used in aircraft, but this is not verified.  Measures ~2.25 inches diameter by ~0.75 inches deep.