Kono Nee-chan, Kaouze!

Busty female student Mao walked into the trap of a gang of boys on her way to school.
They groped her and teased her, and finally thrust their penises into her womanly pussy.

"Let's keep her behind the school and get off!"

With a dog collar around her neck, Mao is "raised" like a sex pet, in class, etc.