Hanahaki disease is a fictional disease where the victim of unrequited or one-sided love begins to vomit or cough up the petals and flowers of a flowering plant growing in their lungs, which will eventually grow large enough to render breathing impossible if left untreated. There is no set flower that blossoms in the lungs but it may be the enamoured's favourite flower or favorite color. It can be cured by the reciprocation of the victim's feelings. These feelings cannot be feelings of friendship but must be feelings of genuine love.

You can't just snap out of it You can't just think happy thoughts And you can't just hope it goes away The truth is It eats you alive Makes you feel hopeless, worthless, unwanted, and unneeded It makes you want to die rather than live with it And you can't see it That's why people dismiss it so often But if we looked like how we feel We would probably be considered hideous in today's world What is it you ask? It's mental illness And we are NOT faking it