Here, the problem is that I cannot render the post with the RStudio project initiated with distill blog.
I can render the usual rmarkdown file with the default project, including Japanese characters in YAML, but as I explained in the question when I tried from the project initiated with distill blog, I get an error.
Anyway, thanks for letting me know that distill allows Japanese in the title YAML. I gonna tweak some settings in my environment and see if distill in my environment allows me to render the post.