Is it possible to pull off a horror anime when the usual style is so deformed towards cuteness and bright colours?
I'm not talking about 1 creepy scene or a cool monster that gets under your skin but a full anime series with a horror focus that is scary. It can be psychological horror, body horror or just a straight up slasher flick that has good tension.
In the 90's we had a lot of body horror and it's well animated but it's rarely scary. It's mostly in action series where the heroes can fight it or are finding some cure for it. Some take it to an apocalypse tier and others keep it on a personal level. There's some creepy ideas there but none of them ever stood out to me as actually scary.
Evangelion has the berserk scene of 01 eating the Angel. It's a creepy scene and I wouldn't downplay that as a horror moment. Same for when the final large angel is about to wreck NERV and the main HQ has been trashed. It's creepy but it's not a full horror series no matter how much of a train wreck Misato is. The slice of life elements interact with the horror where there is always a brighter moment just round the corner. It's tension doesn't build on it's horror elements even in it's darkest episodes (the mind fuck Angel for example). It's a mecha series that has horror elements.
High school of the dead is a horror series but far more horror comedy. It's lewdness is played for jokes while the horror is mostly just things for the heroes to look cool killing. They've never really endanger because a STRONK WOMYN with her wooden sword can kill all the zombies like they're nothing. The atmosphere is horror but the action is not.