Mononoke
Horror is a genre that I usually avoid. Not because I am pvssy or afraid of ghosts, it's actually the reverse I love horror. But most of the horror anime I've seen only from outlook, I never watch them actually. Seem to be relying only on blood, gore and jump scares or shock effect to make us scare instead of focusing on the actual story and creating a terrifying environment. So because all of these reasons I have never actually watch horror anime.
I have seen some episode of hell girl when I was a child but it was dull and lackluster. Until I heard of Ayakashi: Japanese classic tales which was different from other offering in the genre and it was the last episode of Ayakashi which feature the mc of Mononoke which we refer to as " the medicine seller" from now on, which eventually led me to watch Mononoke.
Mononoke is a horror,mystery and supernatural anime produced by studio toei.