Otouto to andoroido to boku is a Japanese movie of 3,336 characters, with 515 unique words and 276 different kanji. Its difficulty rating on Jiten is average, 2.4 out of 5. The full vocabulary list ranks all 515 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.