(virology, dated) virus

(pathology) collagenosis, collagen disease

meeting all three important requirements

(fiction) Hanahaki, an illness affecting those consumed by unrequited love that manifests as the coughing up of flowers, which clears up upon reciprocation. A fictional illness, it has found popularity among both Japanese and foreign online fanfic (especially) artists and authors for its poetic quality.

flat / level / even / smooth

精神分裂病:

to go; to come to one's place / to (a letter) be delivered / to depart / to rely (on a method) / (年が～) to age / (うまく～) to go well / イく: (slang) to have an orgasm, to come, to cum

sacrifice

silkworm

physical education / (by extension) physical exercise