Yeah, I'm thinking the Shapeshifter was the Narrator talking about restoration before Sekai was apparently restored:
She seemed to quickly regret it though based off 'Neverender':
and seemed scared of Sekai towards the end of Beachmas:
The Shapeshifter also seemed to start slanting in 'Shelter':
Not entirely sure why. I am thinking the Shapeshifter has actually been the main Narrator that's not Sensei, since the beginning, now, though.
Btw, Sekai seemed to be the Narrator in 'Imaginary Veins':
The speaking from a female perspective, being called a pedophile by others, and the whole "dig me up, I miss you" stuff seems to imply it's Sekai here.
So, yeah, future Sekai stuff might be The Shapeshifter's fault. Albeit, I think HOPE may have played a part in this being possible:
HOPE may have brought Sekai back, but the Shapeshifter helped restore her. Maybe, idk. This shit is wild.
Can't wait to figure out if I'm right or I'm just fucking delusional. I'm fine with either I suppose. The Sekai-spiracy grows.