National Revolutionary Army
This is a companion discussion topic for the original entry at https://www.ww2incolor.com/gallery/chinese-forces/18941/national-revolutionary-army
This is a companion discussion topic for the original entry at https://www.ww2incolor.com/gallery/chinese-forces/18941/national-revolutionary-army
This looks like a captured "knee-mortar" to me. The name "knee-mortar" was a failed translation of the actual japanese name, which would be closer to "foot-mortar" (as they were often attached to feet to be carried).
There are reports of US-Marines trying to fire the mortar from their knees, which resulted in grave injuries (broken knee or femora).