Swiss Tokei no Nazo is a Japanese novel of 147,253 characters, with 8,896 unique words and 1,921 different kanji. Its difficulty rating on Jiten is hard, 3.0 out of 5. The full vocabulary list ranks all 8,896 words by how often they appear, and you can study them on Jiten or download them as an Anki deck.
Here are some of the words that appear most often in this media, as well as a sample of its rarer vocabulary.