Six hours later, and still no link to the book club thread?
At level 20, you’re still fairly restricted to reading material with furigana, unless you want to spend time looking up kanji. If reading on a computer, this isn’t as big an issue. (And you’re looking up unknown words anyways.)
If you wanted to read something specifically without furigana, but might not be ready to read something completely without furigana, I found 耳をすませば to be a great compromise, as it has furigana on some kanji and not on others. It’s also on the easier side material-wise, if your grammar’s up to the N4 level.