I found these reports when I was in Japan looking for Badgers last month and they might be of interest. No I did not see a Japanese Badger, but thanks for asking. But I did see a few nice things and a trip report is coming soon.
Japan, 2014: Zoothera, 3 weeks & 20 species including Japanese Weasel, Japanese Badger and Japanese Hare.
Japan, 2007: Birdquest, 3 weeks & 17 species including Japanese Badger, Ryuku Rat, Japanese Weasel and Sperm Whale.