Wish this pose had its own tag here. It's cute, no matter if it's for/after sex or just for the pose itself.
Pixiv seldom use the tag "股のぞき" which translates into "Crotch Peeping"

There's the tag combination ''top-down_bottom-up looking_back'' or better ''top-down_bottom-up upside-down'' combination to pull some of them out.