Monsters' Illnesses
The monsters have durable bodies, high demonic energy inside their bodies, and even a strong resistance to disease. Also, although they appear similar to humans, they are different organisms, so most of them don't come down with the same kinds of illnesses as humans. However, there are some peculiar and dreadful illnesses that only afflict monsters. Let's introduce some of them below.
Demon Realm Fever
Monsters normally release a minuscule amount of demonic energy from their bodies, but normally it's under control. When it goes out of control, a huge amount of demonic energy ends up being discharged as a powerful charm spell. The energy of those who contracted the disease that is released as a charm spell will unconsciously target their husband or a man they like if possible. If not, it will pour into any man who approaches, and drive him wild with a powerful lust for the afflicted. Afflicted monsters lose all strength because of a lack of demonic energy. Since they space out and feel feverish while they are afflicted with the illness, even a normally ferocious monster that enjoys raping men will find herself getting thoroughly raped by men driven wild. Additionally, in the middle of sex, energy that is poured inside is immediately converted into demonic energy and continuously poured into the man, so the sex won't end until they both get completely worn out and fall asleep.
It's not an illness that can lead to death. If they rest for a while and get some sleep, they naturally recover. Also, after getting completely worn out after non-stop sex with a man exposed to demonic energy, if she sleeps a whole night while still joined with him, it's even possible to make a full recovery overnight because the demonic energy released by the afflicted goes through his body and returns to her own body, However, if treated through this method, the man who remained joined with the afflicted will definitely change into an incubus due to his body having been continually exposed to large amounts of demonic energy throughout the night.
Pneumania
An illness [2] where the body and instinct of the afflicted feel that there is not enough, even though they do have plenty of mana, causing them to constantly seek more. If monsters who have known the taste of mana, especially the taste of their husband's energy, go a long time without having sex with a man or their husband, and don't absorb mana, then outbreaks may rarely occur.
It's only clear that an outbreak has occurred when the afflicted has sex with a man. They tend to think that they just can't be satisfied since it's been so long since they had sex, but even after tons of sex, the afflicted won't be satisfied. They'll continue to desire energy unlimitedly. No matter what kind of monster she is, once she's tasted energy after an outbreak of this illness, her head will become filled with thoughts of nothing but mana, and she'll become unable to think of anything else until the illness is remedied.
Additionally, since they actually get more than enough energy each time they have sex, the body of the afflicted actually rapidly grows more lusty, and the more sex they have, the more wild the sex becomes. It's an extremely terrible illness.
The disease can be remedied by doing nothing but having sex all day long except while sleeping and repeating this over and over for a while. Since the afflicted convert every single bit of the huge amount of energy poured into them during this time into demonic energy, after making a full recovery, their power as a monster is greatly increased compared to before the outbreak. Afterwards, sex will change, becoming more lewd and wild. Furthermore, the man who kept having sex with them during their treatment will have had to have sex a significant number of times in a short period of time, so he'll definitely change into an incubus during the treatment.
Alraune Pollen Allergy
This is the result if afflicted with alraune pollen allergy. Even the body of a bundle of pride like the vampire gets all sticky, and begins preparing for sex with the man before her eyes.
Outbreaks rarely occur among monsters who breathe in pollen produced by "Alraune". Since all of the alraune became females after the shift to the “new Demon Lord's era”, they no longer use pollen for reproduction, but even now, whenever spring comes, they release pollen infused with demonic energy into the air. The afflicted have the inside of their body violated by demonic energy after breathing it in, and then their body begins to naturally prepare for intercourse with a man. They end up in a state where their body flushes hotly, yearning for a man, the throbbing is intense, their vagina is always wet, and nectar drips out. The saliva, sweat, love juices, etc. of those afflicted with this illness have a sweet fragrance and taste, almost like alraune nectar. Men are lured in by the fragrance, and when they lick it, it melts away their thoughts.
There is no clear way to treat it. Some temporary relief can be had by having sex with a man, but both partners will get all sticky because the larger-than-normal amount of vaginal secretions causes a larger-than-normal amount of semen to be released. Furthermore, it is said that if a man afflicted with ordinary pollen allergy has sex with a person afflicted with alraune pollen allergy, a defensive mechanism kicks in, and the demonic energy infused in the alraune pollen seems to drive away the other pollen, so the man's normal pollen allergy will be cured.
For that reason, scholars expected the alraune pollen to have some kind of curative effect for pollen allergy, but if a man has sex with the afflicted and takes in alraune pollen even once, from then on, he'll become extremely sensitive to alraune pollen. In reaction to the fragrance of the sweet nectar and the slight amount of pollen, etc. released by the afflicted, he'll be overwhelmed by a maddening lust for them, his body will begin preparing for sex, and he won't be able to stand not having sex with them. For that reason, many scholars have expressed the opinion “isn't it simply being overwritten by a more severe form of pollen allergy?” instead of claiming that the original allergy was cured.