Injuries to yukkuri feature prominently in many stories, and there are some common themes. Insanity has its own page.
Non-permanent Injuries[]
Most yukkuri comics show them as being very soft or pillow-like, with no hard bones. They are much more resilient in non-violent stories, with punches and kicks from humans resulting only in a temporarily squashed face, with it returning to normal with no permanent injuries. They are also frequently used as a beanbag chair without complaint. However in the more violent comics, the same amount of force can completely kill a yukkuri by squashing it and spilling its insides everywhere. Of course, there are many stories that also feature yukkuris being able to take insane amounts of damage, beyond anything a food bun could take.
Generally, orange juice acts like medicine for yukkuris. In several stories, it can completely heal most non-fatal injuries. However, depending on the story, it may not be able to reverse severe injuries like loss of eyes/tongues or severe burning.
In fact, depending of the artist, any drinks with sugar can be used to heal them. Even coffee.
Water[]
It is generally agreed that when a yukkuri is immersed in water for a long time, it will start to dissolve and eventually die altogether. (Note: Dissolving is often mistakenly called “melting.”) The length of time and amount of water needed vary by story and artist. Some show that even light rains can cause them to dissolve. Less often, some comics show them able to withstand rain or immersion, merely getting soaked like a dog or cat. There are two main questions that arise from this: can yukkuri saliva dissolve yukkuris, and how do yukkuris bathe themselves?
Yukkuris dissolving to death.
The fandom solved both of this questions, with different results. As a rule of thumb, Yukkuri can withstand a limited exposure to their own saliva, as it's mostly sugary water. Thus, lick lick is an effective way not only to keep a koyukkuri clean, but also as a first aid for small cuts and scrapes. Furthermore, under duress a parent Yukkuri may keep in its mouth as much koyukkuris as it can fit, to protect them from the elements or from an abusive Anon: however, in this latter case, the time of exposure is limited, and some stories are clear in describing how, if the parent is unable to "spit out" its offspring or forgets about them, the huge amount of saliva in a Yukkuri's mouth is enough to dissolve them completely, but also leaving them enough time to curse their parent and try to dig their way out of its mouth, ripping and munching through its body.
As for bathing, in nature Yukkuri simply rarely do. Instead, they resort to grooming themselves by doing clean clean, and especially parent Yukkuris are often seen licking their dirty offspring clean, while for adults its mostly a grooming ritual, like the ones employed by apes.
When they're just too dirty, Yukkuris can bathe for a limited amount of time in a shallow pond, or resort to dust themselves, using fine sand or dust to remove most of the dirt.
Pet Yukkuris are instead shown to be able to withstand limited amounts of water just fine, and the owner is encouraged to clean them by putting warm water and specific detergents in a small cup, or even an eggrest for koyukkuris, delicately massaging them and rinsing them with a watering can, since even the pressure of tap water is enough to tear the skin of juvenile elements.
Furthermore, a water exposure too short to deal permanent damage increases the risk of developing dangerous molds: while this can be avoided with pet yukkuris by the use of special clothes in rainy day, and taking good care to rinse and dry yukkuris, in the wild Yukkuris, during Winter and Summer, resort to long periods of confinment, trying to avoid getting wet by avoiding leaving their nests at all.
Burns[]
Burning the bottom of a yukkuri seems to make them unable to move, at least quickly. They refer to it as their "legs" or "feet". At the very least, koyukkuri seem unable to understand why their "feet" won't "move", and in at least one comic, the mother did not recognize her children's crippled feet. Thus, it seems that even though yukkuri instinctively avoid hot places and generally express displeasure (HWOOOOTTCHHH!), they themselves, in most cases, seem to be unaware of their capability of being crippled by burns, except when told so by other yukkuri that have possibly undergone the traumatizing experience.
Throwing Up[]
A yukkuri may sometimes throw up its filling. This is a symptom of numerous ailments, the most common of which include psychological shock, paste poisoning and trauma-induced acute hypertension. Yukkuri who are very young or have poor constitution to begin with are most at risk. Throwing up bean paste, especially in koyukkuri, is a medical emergency and has poor prognosis in the wild.
Throwing Up may also be the telltale symptom of Anti-yukkuritis: at this stage is still possible to save a koyukkuri, even in the wild, by giving it nutritious food and gently petting it while praising its easiness or comforting the afflicted little one (for example by chanting "Pain, pain fly away" or other comfort phrases). However, the lack of sweet foods and the meager amount of care a yukkuri is able to give in the wild makes that tricky at worst.
Cannibalism[]
According to some fanfiction, once a yukkuri tastes another yukkuri filling (bean paste or anything else), it will become addicted. And it is apparently a good way to prevent invasion in your home: the dog yukkuri-watch will attack and devour with disgusting noises any other yukkuri.
Of course, using a weak yukkuri (like the Mukyukurri) is REALLY not a good idea. The ideal choice is Yukkuri Flandre: its status of alpha predator will make it nearly invincible against common yukkuri.
A surefire way to promote cannibalism between Yukkuris, is offering to a Yukkuri a dead, accessory-less individual or even an accessory-less one unable to speak (for example, by having its mouth caked with flour and dough): the Yukkuri will be unable to aknowledge it even as an "uneasy individual", and instead will believe to have found a real manjuu, thus tasting Yukkuri's filling without any question and without being driven mad by the revelation. However this way they won't be able to connect the taste of the manjuu they believe they've eaten to Yukkuri's filling, thus limiting their cannibalism to a single time issue.
Also in nature, under duress, Yukkuri may decide to relax their rule against cannibalism and offer themselves for consumption to their offspring and family (see: Eat up). City strays are also known to consume the dead bodies of their peers, due to the scarcity of proper nutrition in the human slums and alleys.
One ancient guide at Yukkuri raising suggested leaving in the Yukkurarium the bodies of dead individuals, hinting that by consuming their dead peers Yukkuri are somehow able to carry on physical traits and genetic memories to the next generation. However, later stories partly disproved this theory: while the rationale for the Eat up ritual is still granting koyukkuris enough food to stave off starvation and enough genetic memories to live "easy" without having to be taught by their now dead parent, is still discouraged for the human owner using recognizable Yukkuri bodies as food, to prevent cannibalistic behaviours from arise.
Mold[]
While Yukkuri are generally depicted as immune to traditional pathogens, such as bacteria and viruses, they have been depicted as being susceptible to mold. Mold infestations are generally the result of prolonged exposure to moisture, as water or high humidity. Once established, they can spread rapidly.
Often, the only effective treatment is the removal of the affected skin, which must be done before the mold infiltrates the inner bean paste. Should the mold successfully infiltrate the inner bean paste, the only known effective treatment is to surgically cut the yukkuri open, scrape away all of the mold tendrils, and remove the infected skin as well - a process which, due to the pain involved, is likely to kill the yukkuri. It is unknown whether oral anti-fungal medications intended for human use are effective in ending mold infestations in yukkuri.
While mold is a death sentence for the average Yukkuri, and if the mold tendrils reach the paste core the Yukkuri dies instantly, a very small percentage of moldy Yukkuris die for that reason. As mold usually attaches itself to the bottom part (the "Mister Feet") of the yukkuri, as it's in contact with dirt, poo poo and pee, as a side effect it greatly weakens the skin of the affected individual. While trashing in pain, or attempting to move, the moldy Yukkuri literally rips itself open, bleeding filling.
While common in the wild, Mold is an epidemic, almost endemic condition among the Gutter Trash Yukkuris, who spend their entire life denied of a clean nest, water and fine dust to help in their grooming. Furthermore, as Yukkuri are social beings, mold acts as a contagious plague, with entire Yukkuri family catching the disease by rubbing and licking a single affected family member, hoping to soothe its suffering.
It's also a common sight in the gutters seeing a litter of orphaned koyukkuris attempting to care for a moldy "shister": however, some Yukkuri may become aware of the infectious nature of the Mold, thus refusing to touch a moldy family member, adding psychological distress to its hurtful predicament.
When mold affects a Pet Yukkuri, the only reasonable thing to do is keeping the affected individual quarantined, isolated from other pet Yukkuri or their usual places of dwelling, until the affected individual is cured. If a cure isn't possible, the Yukkuri should be given for disposal to members from the Factory or other authorized individuals, to avoid contamination of the other Yukkuris in the area.
Diyurrhea[]
Much like human diarrhea, is the condition of having an higher than normal number of loose or liquid bowel movements per day. As detailed here, diyurrhea is caused by drinking dirty water from puddles, consuming too much fluid, or getting chilled while sleeping, and it's a common, yet dangerous, disease affecting koyukkuris, with a near-fatal prognosis if left untreated.
A diyurrhoic yukkuri will expel poo poo more watery than usual and with more frequency: as paste filling for a Yukkuri is the equivalent of human blood and tissues, a diyurrhoic yukkuri will basically bleed itself to death, dehydrating its paste core and emptying its own body.
The only known cure is keeping the affected yukkuri in a warm place, feeding it with small, but frequent, doses of high nutrition foods. Despite the healing abilities of orange juice and sugary drinks, a diyurrhoic yukkuri should avoid drinking anything at all: if it does, it will be tempted to drink too much and, while believing to be healing because of the sugar, it will just dilute more its filling leading to the worsening of its conditions.
Constipation[]
The polar opposite of diyurrhea, is the inability for a yukkuri to excrete poo poo. It may have different causes, and every single one of them is lethal for the affected yukkuri, ending in a literal small explosion as the Yukkuri grows increasingly bloated because of its inability to relieve itself of stale paste and falls apart as its skin breaks down.
Koyukkuris and premature yukkuris, much like cubs, are unable to excrete on its own, without being manually stimulated by their parents (who have to lick their bellies). Some parent Yukkuris may also teach their little ones a special "poo poo dance" to help them into control their bowel movements: thus an orphan koyukkuri is likely to die of constipation, if it doesn't manage to learn to poo on its own. However, human owners may rub their koyukkuris belly with a damp cloth, achieving the same effect.
Another form of constipation comes from occlusion: while in the wild a yukkuri may end involuntarily plugging its own anyaru with dirt, pebbles and small pieces of wood that's actually a very rare and unlikely occurrence. A common, natural occurrence of constipation usually happens during winter, when the small koyukkuris are forced to hop and crawl on cold surfaces, thus making their anyaru less elastic and their filling more solid. Usually, wild yukkuris hibernate during winter, or put their koyukkuris under winter confinement, generally avoiding exposure to cold climates, but strays are not so fortunate, and their shoddy nests expose them to the elements, promoting constipation, as their frozen bottom cause a loss of elasticity in their anyaru region and their filling becomes a thick, hard, sherbet-like substance almost unable to be excreted without warming it first.
Barring those peculiar reasons, occlusion, in yukkuris, is mostly the end result of human intervention, abusive or careless. An abusive, sadistic human may be tempted to plug a Yukkuri anyaru with glue, tape or even with flour and orange juice to witness its death by rupturing and its suffering.
Occlusion may also be the end result of ultimate carelessness and ignorance about Yukkuri's anatomy: when a Pet Yukkuri gets its feet damaged, the best course of action if patching them up with flour and orange juice, sometimes using also some manjuu dough as "transplanted skin". A careless Owner may end applying too much flour, or using a large patch of manjuu dough, literally sealing shut the Yukkuri's anyaru, with the same effects of intentional occlusion. According to different stories, such damage is irreversible, or it can be reversed by puncturing the "new" skin in the same place where the anyaru used to be: possibly because of the Yukkuri "belief power", the hole will become a new, functional anyaru.
The Factory and Yukkuri Pet Shops are also known to willingly research and market permanently constipated Yukkuris: the Factory strives to remove the physical need for excreting from the test subjects (always failing, up to now), while the Pet Shops willing sell novelty constipated Mini-Yukkuris for a really low price, to be used as ornaments for cellphones.
Poison[]
According to the majority of stories, Yukkuris have some tolerance for salty foods. House Yukkuris are able to eat crumbs of potato chips but still find sugar and sweets to be “easier,” and one way to stunt Yukkuris’ growth is to salt their water a little, preventing them from drinking and eating as much as they’d want. With some exceptions, they’re utterly unable to process spicy or bitter foods and drinks. Eating or drinking bitter foods may send a Yukkuri into shock, killing it in no time, unless provided with sugar or orange juice to recover. Spicy foods and Tabasco sauce lead to an almost instantaneous death, unless the Yukkuri itself has a spicy filling, such as a the mabō tōfu of a Meiling.
Capsaicin, an active component in chili peppers, in its refined form, such as the one used in self-defense pepper spray, is even more poisonous to Yukkuris other than Meilings. Upon being sprayed with a Capsaicin-based spray, a Non-Meiling Yukkuri undergoes a complete cellular breakdown and ends up throwing up its filling as its body starts to rot, and its body functions slow down to nothingness, the whole time being fully conscious and in pain. Even if it somehow manages to survive, its filling will be unable to process and get rid of the capsaicin, leaving it in pain and poisonous to other Non-Meiling Yukkuris, unable to reproduce, as its filling and body is now a poison in itself, and bear healthy Koyukkuris, as they’d take in poison from the stalk or grow in a highly poisonous environment.
Some farmers have resorted to spraying capsaicin or leaving capsaicin pellets in their gardens, killing off the weaker Yukkuris and letting the contaminated ones destroy their community from the ground up. Unable to grasp the full concept of poison, the surviving Yukkuris, if there still are any, will believe that the “Uneasy Mister Vegetables made them all uneasy” and thus will stay away.