Having played Higurashi, Umineko and Rose Guns Days, i felt like a big similarity between them was the theme of distrust. I'll try to explain while giving as less spoilers as i can, but be careful just to be safe.
For Higurashi:
For Umineko:
For Rose Guns Days:
So, can you identify this theme in Higanbana and Iwaihime as well? Or do you feel i'm mistaken?
Edit (jan 4th) - Having played Higanbana: