This is a self-indulgent explanation of how my version of Hanakanjō works :}

First of all, what is Hanakanjō?  Normally it’s a disease, but my version is a curse. (You've likely heard of its more popular sister, Hanahaki, in which the victim coughs up flower petals when they suffer from one-sided love.)

“Hanakanjō is a (curse) in which flowers start growing out of the victim's body because of a strong emotion. 

Maybe they'll grow when you're happy, feel loved, or at peace! In that case (good emotions), the flowers will sprout painlessly. But maybe they'll grow when you're depressed, anxious, or deeply missing someone... In that case (bad emotions), the flowers will sprout with a sharp pain.” -Urban Dictionary 

✿ In my version, flowers from positive emotions can easily be removed without any pain, but flowers from negative emotions shouldn’t be bothered because they won’t come off harmlessly. 

✿ The type of flowers that grow are based on the language of flowers! Some Examples:foxglove= secrets, snowdrop= consolation/hope, zinnia= friendship, rue= regret, white peonies= bashfulness/shame

✿ The blooms take time to grow, it isn’t instant. Typically a couple of hours pass before flowers reflecting strong emotions fully emerge. (This is why Sundae was able to hide her curse from others for so long.) 

✿ If someone with Hanakanjō suppresses their emotions, good or bad, the effects will pile up, resulting in a sudden bloom burst of the respective flowers aaall over.