Man, this artist's art is so..abstract that I can't even identify the other characters next to Sanae :o.

It's most likely to be Kanako (based on the size) behind Sanae and Suwako (and her hat, Pyonta. Maybe with extra eyes) looking out the window. But, since it's not clear, I'd just leave it as monsters, myself.

The thing behind Sanae is Pyonta, and the ones looking throught the window are Kanako and Suwako maybe?

I really like this one. Kinda gives a bit of a Vasquez vibe.