[Shadow5YA]

Originally Posted by Solace

New chapter is out.

Spoiler for New chapter is out, speculation tagged:

Totally expecting Satomi to turn into a Witch at this point. Again I'm drawn back to the pool of dirty Gems and the revelation in this chapter that Kazumi can "eat" the other clones to regenerate. This may turn out to be the story that explains the origins of Walpurgis. All the signs are there.

Kazumi is a "witch" with no barrier.
She can absorb her clones and has the powers of the other Saints.
The Saints are all on the verge of despair.
The huge number of stored girls on the verge of despair in one spot.
Kyubey is involved, and we know the goal of the Incubators: as much energy output as possible from the creation of a Witch. This would be a huge payload.
Witches absorb elements of their birthplace into their barrier/design. If Kazumi turns into Walpurgis, it would explain the gears: they're all over the place in the museum. The animal parade would be the stuffed animals stored there as well.

Essentially, the theory would be that Kazumi ends up absorbing all of it: the Saints, the stored girls, her own clones, and becomes the uber witch: Walpurgis. She's different from a normal witch in that she has no barrier and possesses multiple powers, and her familiars are the "remnants" of magical girls she absorbed.

I don't like speculating about Walpurgis (I kind of like it being a mystery), but even I have to admit this would be the perfect storm for its origin.

Spoiler for too late:

Kazumi's story begins a bit too late for her to become Walpurgisnacht. The witch is legendary to experienced Puella Magi. If Mami and Kyouko are aware of it, then there's no way Walpurgis can be a new phenomenon created by Kazumi.

And no, there hasn't been any hint that Walpurgisnacht can time travel. Just throwing that out there just in case.