Fujishirou Kousuke is an unfriendly and unsociable high school student. When he was younger, he made a promise with his childhood friend, Sayaka, that they would get married when they grew up. But one day, Kousuke is kidnapped and taken to a place that strangely resembled a prison. Little does he know, is this "prison" is guarded by a very voluptuous woman... Can Kousuke fulfill his promise to Sayaka?