I'm sideloading kepubs, after ripping the books from my amazon account. It just never formats correctly, with ruby getting cut off. I'm frankly tired of it.
I also would love a dedicated device just for reading Japanese books, so I can kind of keep myself in two mindsets. This reader for English, the other one for JP. Even if I wanted one device for it all, I'm sad to say that Japanese books are the only thing you can't get through your standard Kobo account. The Rakuten Japan store doesn't play with the global market, and I get a lot of angry errors when I try to "merge" the accounts. So a 2nd device is the best option it seems.
I do have a kindle, and I read Japanese on it occasionally, but it's a bit chunky for me. I do agree dictionary lookup is better, but I only use the J-J dictionary nowadays, so I don't mind not having a J-E one.
I was not aware the Clara HD had the same chip as the Libra, so I think I might go with that! I think that cinches it, thank you