Flowers pedals...

Art not mine nor are the characters
Hanahaki Disease (花吐き病 (Japanese); 하나하키병 (Korean); 花吐病 (Chinese)) 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