The photo today features a large number of Model 1 Ko "Sallys" of the Hamamatsu School, taking part in the movie "Moyuru Ozora" (Burning Skies).
The markings are random. Many bombers have katakana on their tails, the closest to the camera, probably a Nakajima-built Ki-21, has a "ナ" (na), next to it is a "二" (ni). In the row behind them, the bombers have various bands more common with the usual school markings, but note that none of the aircraft has the Hamamatsu School marking on their tails.
Special thanks to D. Chouinard for stitching the photo.