Hoshi to Lemon no Heya is a Japanese movie of 5,212 characters, with 654 unique words and 357 different kanji. Its difficulty rating on Jiten is hard, 3.1 out of 5. The full vocabulary list ranks all 654 words by how often they appear, and you can study them on Jiten or download them as an Anki deck.
This title is too short to reliably find similar media.
Here are some of the words that appear most often in this media, as well as a sample of its rarer vocabulary.