Kawasaki Ki-32 "Mary" belonging to the Mito Rikugun Hiko Gakko (Mito Army Aviation School). Katakana "RE" on the tail above the school marking.
IJAAF 7.7mm Te-4 flexible machine gun.
IJAAF maintenance students servicing an engine under the watchful eye of an instructor, third from the left.
Thank you very much Jacob for the interesting photos.