
Rakuen Koroshi: Kagami no Naka no Shoujo is a Japanese novel of 252,026 characters, with 11,560 unique words and 2,081 different kanji. Its difficulty rating on Jiten is hard, 3.6 out of 5. The full vocabulary list ranks all 11,560 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.