Having never watched anime before, I was convinced by a friend to watch a show called "Higurashi No Naku Koro Ni". Epic shit was epic. Basically 13 hours of torture, murder and lulz. Not just scary based on a factor of violence but on suspense. It really took some thought to understand this show. It has various "arcs" or storylines. They all try to explain this disease called "Hinamizawa syndrome" .
Many people in the town of Hinamizawa start going fucking nut balls because most everyone in the town has it, and the various stages of it can cause nothing, to mild paranoia, to slitting your own throat with their own finger nails.
Every arc shows the unraveling of the friendships between the main characters, ranging from them lying to each other, to them torturing and killing one another. Here is a video so you can see most of the epic scenes from it. And here is another link where you can watch the whole series.
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