The two things are quite unrelated and only connected by one important story element. Definitely read the book first (also to let your imagination not be 'poiso

The two things are quite unrelated and only connected by one important story element. Definitely read the book first (also to let your imagination not be 'poisoned' by the game's art style), but then be prepared that the game doesn't have much in common with the book except this one story element.