Higurashi is highly regarded, reasonably popular and a very easy entry point into psychological horror / mystery. If you care about what you are watching you probably should have seen it before you even know what a yandere is and especially before asking about shows that specific. These two are the only ones that ever come up when talking about yandere in the first place. I don't watch current season so is yandere as common and tsundere in your generic harem romances nowadays?