Kyoto University has released the North China Transportation Company archive of photographs. It is entirely in Japanese and the translation is a little awkward. I wouldn’t have found this at all, though, if it weren’t for the help of David Hajime Kornhauser at Kyoto University. Thank you so much, David! Anyway, Wikipedia has an overview of the North China Transportation Company and its history, and the archive has collections of photographs broken out by year, from 1936 to 1945 (1939 has the highest count.) Photographs are also organized by what I think is location and by AI tag.
If you have any interest at all in photography archives I encourage you to visit this one; each image I looked at had a toggle to the right that allowed you to switch between the original black and white photograph and a version colorized by AI. Here’s a side by side comparison of one such image:
An article in the South China Morning Post has more about the archive and its background, as well as the response of some on Chinese social media to the release of this archive.