吾輩は猫である

This is a lot harder than people seem to think it is. It's not so bad if you just want to understand on the level of "the narrator is a cat haha - some funny stuff happens with his owner and his owner's friends." That is to say, the basic plot - to the extent that it even exists - isn't too hard to follow. The soul of the book, however, is in the humor and the references, so if you don't follow those (and I often didn't, e.g. because I don't know the names of Imperial Japanese admirals or historical Chinese poets) much of the writing falls flat. I've heard that there are annotated editions explaining the allusions - if I'd had one I might have had an easier time.

If you just want to read something by Soseki, read こころ instead - it's much easier. Or read this, but stop after the first chapter or two, before you get tangled up in the hard parts.

Lots of rare kanji, but as you'll have plenty of furigana this isn't much of an issue.