MMD Tutorial - Braviary's tail's problem

Here's the tutorial on the problem of Braviary.
I hope it will help.

Models (I still have credit even in a tutorial) :

Elsa by and

Braviary by and fixed by

Manaphy by

Pikachu by and roxas358

Stage by Dandis Shiruhane

Skydome by Ussy-P

Elsa from Frozen and belongs to Disney / Hans Christian Andersen

Pikachu, Braviary and Manaphy from Pokemon and belongs to Satoshi Tajiri