While menhera as its own aesthetic and movement may be new, the whole glorification and romanticization of mental illness in VK is anything new. There were songs about struggling with depression as early as the 80s, see some X Japan songs. I remember when I stumbled upon their Weekend PV back when I was an edgy and super angsty teen and feeling so connected to it because it’s very tragic and has the bandmembers being miserable.
Then the whole 90s Kote kei scene had a real obsession with “being mad” and “insane”. Madeth gray’ll even began one of their songs with Hisui mumbling how crazy he was in his head. Bands like La’Mule would also simulate cutting live (so many songs had “Wrist Cut” in the lyrics or even title). I think La’Mule’s Kon even self harmed for real. If I remember correctly, he was in no good place in the NightingeiL days either and posted blog entries of his wounds… so this whole thing isn’t new, it’s been part of VK for a long time, if not since the beginning. Hell, I would even go so far and claim VK was specifically designed to appeal to social outcasts and “weirdos” who identify with the whole “troubled artist” stereotype.
It’s also partly due to VK’s musical ancestry going back to Punk (in some parts). I am befriended with many punks (though I am personally more into Goth and Post-Punk). The amount of self destruction via drugs, alcohol and physical harm is something that kinda puts me off, even though I like the music and the people are otherwise really cool. But being miserable is still seen there as kinda “counter-culture”. Ironically, Goth has since long moved away from that and is mainly about music these days. In the end it depends; as long as mental illness will be considered out of the norm there will be scenes, movements and fashion trends that try to make it into a trendy thing or a statement, because it’s easy to brand as “anti-mainstream”.