I don't think it's been confirmed either way. Makes me wonder if it would be correct to tag this as FF just yet, seeing as the braids may count as accessories, and we all know what happens if there are...
Being more of an FF fan than abuse, I'd like to think its true, but most of the time you see Yukkuri go bat shit insane from losing their braids/flapflaps so I think this is a pretty heavy troll towards the Reimu.
Too bad, it looks pretty good with that ruffled hair too.
Hmm the thing is, is that there has never being shown any yukkuri that really grew back their hair or accessory.
In fact they usually remain like that for the rest of their time in the stories or comics.
Which leads me to think that they really can't regrow them.
Which actually would make sense if you consider that they never grew them out to begin with, they were born with them and it only grows proportionally to them, like some big that you use since a kid and somehow has the magical propierty of growing up with you, but if you take it away, a new wig won't grow to remplace it.
Well we are shown stories on which yukkuris aren't necessarily kill by humans or their peers minutes later of that event, even if days happen, there is no notorious change.
Being honest i think it would be plausible for a creature like the yukkuris to lack the capacity of regrowing stuff like teeths or hair and accessories.
They are born with them since day 1, they never change them and they grow with them proportionally.
It may be related to the fact that yukkuris also lack even a basic level of self regeneration without lick lick, since if they let the wound there, it would remain the same, until someone licked it and without realizing it made the dough wet and able to mix and join again in the wound area.
In some stories, it is said that you have to introduce in the yuukuri liquid candy (or something like that) to create the paste core. With the paste core created; the yukkuri can reggenerate ,virtually; any part IF the wound isn't deadly.
Usually, most of the stories are about wild yukkuri. This means there is no one who can place the liquid candy in and thus, no paste core and no regeneration.
^Actually, I do believe there's been a few stories/images that have wild yukkuri have paste cores.
My theory: Paste cores are an 'artificially' induced evolution. It originated when someone used liquid candy(I thought it was starch, but who cares.) to cause a yukkuri to have a paste core, and that particular yukkuri escaped/was released into the wild. Because the Paste core makes the yukkuri more resilient to damage, it would be considered a beneficial evolution. Thus any children born from a paste core yukkuri would also have paste cores; leading to some portion of wild yukkuris having paste cores after a decent number of generations.