User blog comment:Xilinoc/Ch. 668 - BIGGER,FASTER,STRONGER/@comment-1970092-20160331203556/@comment-11293956-20160401192549

Zanpakuto spirits don't just give out Bankais. They learn it when their Shinigami does. Yachiru/Nozarashi being able to give Kanpachi his Bankai implies that they already had it which is extremely unlikely as he just recently got his Shikai...then again, this is Kubo's series and he can change concepts and rules as he pleases.