Ebihara Urara's fiance disappears after incurring significant debts. As guarantor, she is coerced into joining the faculty of Kurodou Academy by the debt collector Kijima with the promise of wiping out the interests on the debts.

Believing that her fiance would come for her, Urara gives in to Kijima and transfers to Kurodou. However, what she found there was the deepest pit of depravity...