I seem to recall good support for PC98[0][1] was seminal. Our friend ‘washbear has notes[2], which might be touching on (eg) KAME[3] too.

[0] https://en.wikipedia.org/wiki/PC-98

[1] https://hackaday.com/2023/12/26/the-strange-world-of-japans-...

[2] https://news.ycombinator.com/item?id=32375371

[3] https://en.wikipedia.org/wiki/KAME_project

PC98 support grew from the facts on the ground: NetBSD and friends had Japanese-language mailing lists and irc channels, for decades

If you were a Japanese enthusiast who wanted to have a "real UNIX" on readily available hardware, NetBSD and FreeBSD were relatively more accessible

NetBSD did change their 'logo; to a single flag years ago. And I heard the same also.