As I'm adding words to my Japanese keywords list for RTK I'm making all kinds of interesting discoveries along the way, especially with regard to the less common kanji. Frame 786 is 翁, "venerable old man". I didn't know any words including that character, so I looked it up and found this - 翁の面, "an old man's mask". The first thing I thought was "I didn't know old men habitually wore masks", but, Google image search to the rescue, and it turns out it's actually a mask made like an old man's face, as shown in the picture. I imagine it would have some theatrical or ritual use but didn't investigate further.