>>49350141
I don't think being deathly afraid would be that different from the average villager and, based on some of the supplemental material, a happy human is more delicious(probably in both terms of fear and body).
However, if they somehow caused a fear surplus, I think the Youkai would just grow fat and lazy since they're too satisfied. It would be a whole different problem.

If often happens in fanworks and Youkai monster girl manga were the MC has something about him that causes monsters to go nuts such as "you smell like the country", "I had an unrequited love with your distant relative and now I want to fulfill it/get revenge on his bloodline.", and of course "The scared/shocked look on your face is delicious".
It doesn't do much for me usually, feels like it's just generic for the sake of wide-market appeal and doesn't provide much characterization. One idea I had to solve this is to introduce a human who's incredibly easy to possess and doesn't remember what he's done while inhabited. I would call the series "Highly Vulnerable to Possession" and make it a mystery story where he often is made out to be the culprit for crimes.
Sort of like Yuyuko's ability, the trait should seem like a curse, but the truth is that it's actually a sort of ability. For the Possessed, I would reveal that the reason for his weakness is because he has incredibly talent as a medium, borne out of his love for hosting meals, so he's a good host because he's a good host.
It'll feel more like Touhou when the character has a troublesome, esoteric ability the reader can reason about is what I think I'm trying to say.