Curing yukkuris with orange juice is as simple as pouring it all over them, though injections and ampoules also work. It's capable of healing bruises, injuries, burn wounds, restoring paste loss, removing mold, curing diseases like yu-diarrhea, and in some works can even cure them of mental diseases like anti-yukkuritis.
However orange juices cannot cure very severe skin loss injuries, for example a yukkuri is cut in half can be reconnected with orange juice but if said severed half is gone for some reason then the yukkuri won't grow new skin. Still, such injuries can typically still be repaired by replacing the lost parts with new parts made from flour dough, connecting them with the yukkuri and then pouring orange juice all over them.
The one thing it can't do is restoring lost organs such as eye loss or hair loss. Replacing these with flour dough won't work as they're more intricate parts than skin. If one needs to replace hair, braids or eyes, the best thing you can do is finding a substitute obtained from another same-species yukkuri, usually taking it from them through "unpleasant means". Using different species yukkuris can also work but it'll lead them to become weird hybrids. While they themselves won't always mind being a hybrid it might get them to be rejected by their fellow yukkuris.
A common mistake among beginners is using other orange byproducts instead of juice(such as orange soda). This usually hurts the yukkuri instead.
It was originally invented as a yu-lover item to heal niceheads or pets who was hurt by shitheads. Ironically though, nowdays it's seen more as an abyuser item, used to keep the yukkuri alive for as long as possible to prolong the torture that can be done to it.
The incredible potency of orange juice's effect of healing yukkuri's is most obvious when performing abuse that involves submerging the yukkuri in orange juice. If a yukkuri is submerged in an orange juice that is boiling, freezing, or mixed with poison (such as coffee or hot sauce); then the yukkuri will corrode for a brief moment before the orange juice immediately heals them. This doesn't prevent the pain and can cause deformations but generally the yukkuri will survive. Hell you can even simply drown the yukkuri in normal orange juice and it will heal faster than it could melt.