oh god please not yuno from mirai nikki, she's a standard generic yandere that isn't necessary a good example for a dateable character - if i may suggest a good example of a yandere, i'd suggest Zahid from Please Don't Eat Me and Dylan from Taming of the Tyrant which are both webtoons. One of them gives the feeling of dancing on the tip of a knife and the other feel almost like a green flag until you see all the red and that's a good way to play with yanderes as opposed to just red flags abroad from the start IMO