While a comprehensive Japanese to English instrument cluster conversion can be performed via the OBD2 diagnostics port for both the Nissan Leaf and eNV200, the same process does work for the audio/navigation system (also referred to as a head unit). The conversion process for these is approached differently and depends on the model/spec of your vehicle.
On the lower specification Japanese models like the Leaf S or the e-NV200 VX & GX the easy solution is to replace the original audio/navigation unit with any aftermarket unit that has the desired features and appearance. More information on this can be found below.
On the higher specification Japanese models like the Leaf X & G or the e-NV200 G, the original audio/navigation unit should only be replaced with a unit specifically designed for that year/model car or else significant functionality will be lost. For further information on converting or replacing the head unit on these models, please check out the following information.