CotEditor (https://coteditor.com) is a well written, open-source (https://github.com/coteditor/CotEditor), lightweight, native (Swift), lightweight plain-text editor that many Chinese, Japanese, and Korean developers love to use. I highly recommend it.
Yeah, I believe it is made by Japanese devs.
CotEditor has excellent typography support. Invaluable for testing fonts.
Looks very nice.
Is it nicer to install it from the AppStore or from homebrew, I wonder?
I use MacPorts anyway, and for software like this I use App Store since it’s not like I can avoid using my Apple ID these days anyway… (Which is slightly bothering, but off topic.)