This is a hard haiku constraint set because DEMUR is formal, slightly stiff, and not naturally imagistic, while LEMUR and FEMUR pull the poem toward rhyme-chain and novelty. That combination can make a haiku feel like it is solving sound before scene. auntie jj’s “MOPER did WORST CRIME / whacked LEMUR in the FEMUR / fessed up, no DEMUR” is a strong example of handling that well: the constraint words are absorbed into one compact narrative, so DEMUR arrives as a real behavioral outcome rather than a vocabulary tag. Across the set, the stronger poems survive the difficulty by giving the rhyme-heavy words an actual job inside a scene — confession, warning, refusal, or transaction — which keeps the haiku from collapsing into mere wordplay.