A interesting video and article by Mainichi. I am a little surprised to see that the axles use journal bearings. Although a number of these have been scrapped, there are still 13 in use.
Google translated article: https://mainichi-jp.translate.goog/articles/20240504/k00/00m/040/032000c?_x_tr_sl=ja&_x_tr_tl=en&_x_tr_hl=en&_x_tr_pto=wapp
Google translated Wikipedia page on WOKIFU 100: https://ja-m-wikipedia-org.translate.goog/wiki/秩父鉄道ヲキ・ヲキフ100形貨車?_x_tr_sl=ja&_x_tr_tl=en&_x_tr_hl=en&_x_tr_pto=wapp