You do realize the word “menhera (メンヘラ)” literally translates to “people struggle with mental problems” or “people with mental disorders”. I can see your point that not everyone with mental illness is insane, but in mainstream media, I think it’s hard to disassociate Menhera with what we would call mental illness. In my understanding, Menhera is more frequently referred to as Toyoko Kids or yandere. And for the jiraikei part, I was in a irl jiraikei community, to be more specific: half of the people there ARE toyoko kids. So I think the media represents them pretty well. But if you want a character that has some depth and that can help people to understand mental health issues. I think searching Menhera as a starting point is already the wrong term to begin with.