Kangoku Onna: Dasshutsu Fukanou no Injoku Shisetsu

"The prison island is reborn as a facility of inescapable fornication." It was a locked down island fortress. Nobody ever got free. As long as it had been home to criminals, jailbreaks were attempted. They all ended in failure. The prisoners didn't give up, and had a final plan. If they couldn't get past the guards and the barren walls, they would die by police suicide. R*pe the guards, and go out in a glorious orgy. Three years passed—At last, the plan was ready. With all prisoners conspired, the cells were opened and the prisoners slipped out, stabbing the patroller as they made their way down the corridors. Having meticulously researched each step, they knew they had the upper hand for about one hour. But...There was no boat. 30 kilometers of ocean separated them from freedom... (Source: dlsite)