Sorry for the long absence, I was learning new tricks. During this time, my mascot Kai got a significant upgrade. I tried to make her look more like a monster in human form.
The tail was made by me, as was her costume, except for the rings and nails on her hands and the earrings in her ears. Also I made changes to the materials (added glow) and to her face. And I manually added support for ARKit Expression! I have a lot to be proud of. This was the longest activity, but I got through it.
For the reference model and tutorial on the subject, thanks a lot to the author hinzka hub.vroid.com/users/167011
(Don't advise me HANA Tools, I know about it, but I can't afford it yet)