I don’t know the answer to your question- sorry!
Just would like to mention a couple of things that might be relevant:
- If you want to go that way and find a book you are interested in reading available as an ebook (unfortunately sometimes I can’t find books I want as an ebook, it’s happened to me several times with Keigo Higashino and surprised me a lot as he’s such a reknown author), after going through some hoops it is possible to read the book in your browser and thus make full use of plug-ins with instant dictionary lookup (such as Yomichan). Using this method, I’ve been able to read real books way before I was “able to read books” (though I am also using Satori Reader and still finding value in it!)
- I am about to read my first Keigo Higashino and can’t talk all too much about it yet as I’ve only read the first page, but I was really surprised to see that I could understand everything in said first page, maybe have a look and judge by yourself if it’s as hard as you expect: