i'm guessing its some sort of upgrade to some of the swords

but so far the only info is that they have to be at least level 60

and you have to have cleared stage 6 and gotten the three items that drop from the last stage

the items are supposedly needed to advance them to kiwame

from the silhouettes, the leftmost looks like midare the rightmost gokotai?

the one next to maybe-gokotai seems like Hirano?

the helmet one might be Atsu??

they do seem like it

Hirano's hair is short and neat enough to fit

and I don't see Maeda's cape or Akita's armour shape

They're finally going to use their Noble Phantasm?