HIgurashi is a terrible anime/manga/visual novel series that retcons itself with too many pointless "arcs". Fucking hell, may as well just call it ground hog day.
Higurashi is pretty good IMO, if a little long. How does it retcon itself. I only read the VN but the VN was great.
Basically no matter how times Rika dies, the entire timeline for the anime/manga/vn repeats itself. Sometimes the same scenes from the manga rewinds into the anime, except certain characters end up doing different things...
Thats not a retcon... did you watch groundhog day? ---