#noh

But surprise, he is found in the depths of Central 46 privet living space, isolated from the outside world. He is revealing himself to Hinamori, and to the audience, not only to be alive but to be the villain of the series. His gentle mask is gone, and a devious smile is plastered to his face.

When Renji says: You don't act like Captain Aizen I knew, he answers: Captain Aizen you thought you knew never existed in the first place - confirming that his gentle identity was fake, a mask he wore all these years for the Gotei as his audience.

Then in the beam of yellow Negatione, Aizen and the two followers of his get carried up by the Menos Grande to the sky - apotheosis.

End of the play.

So what is considered one of the biggest plot twist in the history of anime (Aizen's villain reveal) when read through the lens of a Noh play structure becomes expected outcome. But to see this, let me tell you more about Noh.

Noh (能, Nō) is a traditional theater form born in Japan (Muromachi Era, 1333-1573).

There are 2 actors in Noh: main actor, main protagonist (shite) + supporting actor (waki). The shite plays a double role: appearing first as a common human, and then as a ghost, demon, or god (kami) - the first role is known as the mae-shite and the later as the nochi-shite.

Only shite wears a mask.

The play has 2 parts, in first act waki meets shite but doesn't know their 'true' identity yet. Then shite returns off-stage through the bridge (hashigakari). And at the start of the second act the reveal takes place. The shite returns wearing a new mask, crossing the bridge again, which is a symbolic connection between the world of spirits and the world of the living (liminal space). And the new mask is a mask representing a true identity of the character: oh, this old lady was a kitsune demon - the waki finds out.

So as you can see, there is no real twist - the change of the identity is expected from the start by the audience that knows that structure, it is only the play character who is surprised, or who learns the secret.

And symbolically the very similar thing happens with Aizen. He is pretending, wearing a mask of the every-man, just to reveal himself to be something more than an average shinigami. He goes into hiding into his liminal space, the world of the spirits, and returns as a mastermind who has planned that all. Wearing a new mask - a mask of a god, who wants to stand above the heavens.