Koyomi knows the story of Kanbaru Suruga’s bath sometimes reflecting the image of the person you’ll end up with someday. He’s not sure that means he’ll be able to use it to return to his world or contact Shinobu, but he thought he’d give it a try—and meet a Suruga who might not be lewd, masochistic, or immodest.
Turns out she’s none of those things. Instead, she’s the Rainy Devil: pure rage, hatred, and pain. He can’t get anywhere near the bath, and is only rescued from the devil’s wrath by Mirror Tsubasa, who is simply Black Hanekawa. She warns him not to go back to the bath without a specialist, but that makes two consecutive friends of his who are the oddity versions of themselves in this world.
If Suruga’s Mirror self is a nightmare, Mirror Oikura Sodachi is a good dream, or rather a “good ending” version of the character, who moved in with the Araragi family when she was in grade school and is now something of a third sister to Koyomi, and thus extremely affectionate towards him. Still, as happy and blessed as she feels, a part of her can’t help but wonder…is it all a lie?
If you were to ask Mirror Nadeko, AKA Kuchinawa-san, the answer is no—and Koyomi gets to ask her, thanks to Big Sis Mayoi inviting her predecessor to the shrine to help him work through his predicament. Mayoi also tells Koyomi to loosen up and enjoy himself, and she starts imbibing bottle after bottle of sake.
Kuchinawa knows about mirrors; the root of the Japanese word for mirror is “serpent’s eye”, and mirrors were first used as a holy instrument, not to reflect an image, but to reflect its truth. Put simply, each and every person Koyomi has met so far is no less the real person as the ones he knows in his own world.
The mirror he finds himself in doesn’t just flip them left-to-right, but shows the other side of those people. That explains why Tsukihi is the same; she has no other sides. If this world is, as he previously considered, the product of an oddity that exists for a reason, perhaps the key to dealing with that oddity (if that’s what it is) is to be exposed to and accept these other sides as equally valid…