I went ahead and installed it. It seems to work fine. I don’t know if it’ll meet your needs, but all you have to do is stick it in .kobo/custom-dict/.
The first pic is from my Libra Colour, and the second is from my Elipsa 1.
My LC is natively English, so highlighting Japanese words in vertical text is a bit fiddly. Doesn’t always work.
My Elipsa is natively Japanese and it doesn’t have the selection problems that the English language LC does.
I just chose two words at random. Is there something that you’re specifically looking for? You could probably just install it yourself and get the answer faster.