Honestly, I think it's "The World" or maybe Sekai, that tends to speak to Yasu at times which causes her to foreshadow things.
Similar happened with Makoto's dad:
and presumably with Rin around the Sensei Quiz:
Both of which, like the phone call with Otoha, has Yasu seemingly foreshadowing bad things happening which ended up with girls sad.
Yasu's also mentioned an interference that's related to the ocean:
I'm assuming she's referring to the beach, where sad things tend to happen, and it just so happens to be where Sekai got restored, then ended up seemingly claiming Yasu. Could be wrong, though.