Kirk here. This forum got started as a mailing list to help get the word out about a labor movement involving non-Japanese teachers at the Prefectural University of Kumamoto:

Kumamoto General Union vs. the Prefectural University of Kumamoto: Reviewing the Decision Rendered by the Kumamoto District Court https://www.degruyter.com/document/doi/10.21832/9781847698704-007/html

In that connection, I think the following issue at Nagasaki University is relevant:

English teacher to sue Nagasaki U. over dismissal day before unfixed contract eligibility https://mainichi.jp/english/articles/20190826/p2a/00m/0dm/013000c?fbclid=IwAR1lBmvb3gLse9KlIIrN80-C-G58eUluQseuleM0gcB_oA5Ilv6X82YvdRQ

Although I haven’t seen anything in English yet, Japanese-language reports indicate that he won – unlike the Kumamoto suit, which ended in defeat.

元助教の雇い止め訴訟 長崎大に賃金支払い命じる判決 地裁 https://www3.nhk.or.jp/lnews/nagasaki/20230130/5030017102.html

I’ll try to provide more information about the judgment when I have more time or when an English-language article comes out.

P.S. Thanks to Joe Tomei for the heads-up.