The BAe125 (and all of the successor names) was a dominant biz jet for many years. It also found a few roles in military operations from transport, through trainer, to flight calibration and reconnaissance. The JASDF was one such operator with the aircraft designated U-125 in Japanese service. Hyakuri is home to a detachment and one of the jets flew during my visit. It taxied out and headed off on its mission.
Returning later on it was stopped in time to make the taxiway not far passed my location. The aircraft has a fairing underneath the fuselage for the search radar. The operator sits in the fuselage just above this location. They are also provided with a huge observation window for observing what is going on outside. Must be a good spot for taking pictures! I’m not jealous…