For those interested in making notation, I found this today:

http://fluteywinds.com/japoscore/

If I understand correctly, this software was initially developed for Shakuhachi notation and then expanded to koto and shamisen. It produces notation mainly in the Japanese traditional right-to-left vertical format, however I think bunkafu might be an option based on a screenshot on the back of the catalog: http://japoscore.fluteywinds.com/wp-content/uploads/2019/06/JapoScoreFlyerBack.pdf

Here’s the English handbook:

https://fluteywinds.com/japoscore/handbook2-5eng/