四畳半神話大系

Initially difficult but entertaining

The book's narrator is a university student (and somewhat full of himself), so maybe it's only natural that he tends to use a wide vocabulary and fancy, roundabout ways of expression. I wouldn't even notice it in a language I was fluent in, but in Japanese it resulted in many, many lookups, and the need to pay extra attention. That said, several passages are repeated multiple times, sometimes even verbatim, so by the end of the book it didn't feel any more difficult than any other book I've read