Meeting the Heart-Under-Blade of this world is not what Araragi expected. Before he knows it, he feels compelled not only to bend the knee, but admonish himself in his thoughts whenever he says anything to her, culminating in him getting suicidal thoughts. Turns out that’s what happens with anyone (other than Ononoki) in her presence; her glory is just too great for any mortal to behold.
But in their short time together, Shinobu tells him a great many things he hadn’t considered, like the very real possibility he’s not the “victim” of this incident, as he has thusfar assumed, but a negative influence on her world, throwing it and everyone inhabiting it out of balance. Basically, he has to return to his world, and is on the right path, but he won’t be able to do it alone; he’ll need aid.
When Ononoki lists all of the qualifications required for said aid, a part of me hoped Senjougahara Hitagi’s name would come up—perhaps she’s a specialist in this world?—but the answer is the most obvious: Ononoki herself.
After his encounter with Shinobu, Koyomi immediately starts to notice the so-far subtle effect his presence in this world is having on those closest to him, particularly Sodachi. But while Tsukihi is giving him a compulsory face wash, he spots the other Koyomi in the reflection of the water in the sink.
After contemplating the possibility his own home might be the gate back to his world, Ononoki brings up an alternative plan: simply learn to live here and let the world change him, rather than the other way around. Perhaps his influence is only negative because he’s fighting the reality of this place; “giving up”, so to speak, could reverse the direction of influence.
Koyomi tables this idea, as he’s not sure it’s even achievable – even if he outwardly goes along with everything, there’s still his subconscious to consider, not to mention he has too much to do in that world to leave it now.
So instead it’s off to Kanbaru’s. Ononoki is supremely confident she can hold the Rainy Devil off indefinitely, and certainly as long as Koyomi needs to do. When simply looking in the reflection of the cypress bath nets no result, he strips and takes a bath.
That’s when Kanbaru’s mother Gaen Tooe enters and demands to know who he is before she ends him. No empty threat, but between the Rainy Devil and Tooe, Koyomi’s Araragi Charm will hopefully be more effective on the latter.