Hitsuji o Meguru Bouken is a Japanese novel of 199,910 characters, with 9,349 unique words and 1,807 different kanji. Its difficulty rating on Jiten is hard, 3.3 out of 5. The full vocabulary list ranks all 9,349 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.