"Ancient" and you ain't even 30 yet lol
I'm 33 and I know people way older than me that know of hanahaki disease.
In terms of tropes it's not really used that often, but it isn't a "verse." Verse implies there are two sides. Alphas and omegas. Espers and their guides. Forks and... cakes...
Anyways, hanahaki is a disease caused by unrequited love and can lead to the death of the one afflicted. If the love becomes mutual, the disease goes away. If it remains unrequited then the person runs the risk of dying 'cause the flowers literally sprout from inside their lungs, ultimately drowning them.

How many of you have never heard of the hanahaki disease? It's not something new, its been here for a while.