
It is a taboo story about love and incest between twins. It's not about sex, it's about the feelings the two have for one another and how society views them.
Boku wa Imouto ni Koi wo Suru is a Japanese movie of 5,839 characters, with 660 unique words and 302 different kanji. Its difficulty rating on Jiten is easy, 1.6 out of 5. The full vocabulary list ranks all 660 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.