Four girls are kidnapped and gathered at their old school, which has been closed down. Before they know it, they're half-naked and have bells on their nipples? This was a place where boys who were bullied by girls in their school days could get revenge in a game called 'Impregnation Tag'. The boys then tampered with the lock and released two sex beasts into a classroom where the girls cannot escape on their own. The sex beasts were trained to react to sound and immediately insert themselves into their prey (girls). The girls carefully escape within the classroom, trying not to ring the bells attached to their nipples. Who will be able to escape and get out of the classroom within the time limit... and who will have the bully's grudge spark in their vagina?