FloFlo is a website created by Raionus which is designed to help people overcome the vocabulary barrier of reading Japanese.
You can get a list of vocabulary from a particular book, which is ordered by appearance and can be filtered by the frequency at which the words appear, and then load them into an SRS to learn them.
So for example, before reading 時をかける少女 I pre-learnt all the words which appear 3 or more times in the text, and now that I’m reading it I’m using it a bit like a prescient dictionary and learning any lower-frequency words which seem useful / will appear in books I want to read in future.