A quick google suggests it is a fuel metering unit.

The ECM controls the fuel injection system through the EDU, injectors, and supply pump.
The ECM determines the injection volume and injection timing based on signals from the accelerator pedal position sensor, crankshaft position sensor, and camshaft position sensor. Based on the signals from the ECM, the EDU controls the injectors. The EDU also controls the suction control valve installed on the supply pump to help regulate fuel pressure.
The piezo type injector used in the 2AD-FHV engine makes noise when the engine is idling because this injector operates at high speed. Therefore, the EDU controls the injector to operate at low speed when the engine is idling based on signals from the ECM to achieve noise reduction.
The feed pump is used to pump fuel from the fuel tank to the supply pump.