Pre-Modern Japanese: Japan reformed their writing system in 1900, making all of their writing from 800-1900 unreadable to all but a handful of specially trained scholars. Thus many interesting and practically important documents such as the following guide on how to identify fish people are unreadable by the average Japanese person!
To help address this, we've built an ML system which can recognize the Japanese characters! Check out some results (blue is ground truth, green is predicted, errors are marked with a red X):
