/jp/ - Otaku Culture

I'm convinced that Sonozaki Shion does not physically exist as a separate person from Sonozaki Mion. Even though she's onscreen with Sonozaki Mion at the same time, that can't be proof enough that she's actually there. It's the same as when Hanyuu suddenly has physicality in episode 8 even though she was just an entity that only Rika could see. Sonozaki Shion, too, is just another "entity" or "personality" within Sonozaki Mion that is granted physicality in Watanagashi onward.
I think this because first, in episode 5, "Shion" can't even differentiate who "Mion" and "Shion" are as entities. There's a singular physical Sonozaki but two personalities that mesh inside her brain: https://i.imgur.com/GmcZiPi.png
Second, earlier in the episode when Ooishi sneaks up on Satoshi and Shion pretending to be Mion, Shion declares to Ooishi that she is in fact Sonozaki Shion. Ooishi has no idea who Shion is even though he's dug up as much information on every club member and their families as possible. It can't be that Oryou just kept Shion's existence hidden from the world when Ooishi has shown that he has a mole in the Sonozaki Clan.
Shion never appears in Onikakushi. Rika first meets Shion at a funeral, and Oryou even discusses how sad it is to lose a grandchild. (https://i.imgur.com/iANPgLx.png))

It's possible that Shion existed as a person at one point and died and now Mion is left with two personalities she switches between.