Danganronpa 3: The End of Kibougamine Gakuen - Zetsubou-hen

Both series feature characters in highschool more or less having fun, but tensions start to build up during the show and in the end things end up really bad for basically everyone involved. Both are an example of a school anime gone wrong. In School Days things go wrong because of the characters themselves, while in Danganronpa 3 Zetsubou-hen a person outside of the group causes everything to end up bad. 

Both animes talks about a school and a tragedy, also, they are made by the same studio, they have samiliar vibes, and both are great! 

Both animes are prequel animes based on a video game franchise  

I think the idea of despair as presented by Danganronpa is somewhat similar to Higurashi's general feeling. I think both anime have a relatively similar atmosphere, one filled with murders, mysteries and conspiracies; and a generally similar level of edginess and cruelty. 

In both series we watch the road stories where the good main characters was turn into the merciless villains. 

Both of these series are about putting its young characters through despair as their mental strenght is tested and on the brink of breaking. 

Both being prequels of their respective story timelines and tells about the series of events that lead to the eventual decline and destruction of the world.