The Lazy Text Tool can do vertical to some extent, but that is for single line. So while it would work easier than say just typing it manually, it still would be a tad difficult because it wasn’t really made with multiline vertical support in mind. So you would still have to do 1 line at a time.
But if there is a demand for that, it should be possible to implement in the final version.
Unfortunately, the current tool doesn’t support that well. Well, you can do it if you input the svg data into the text tool but that would be difficult.
Give me a short bit and I think I can make a simply python script that can make it work. They don’t need anything like bold or etc, just set japanese font and text right?