Yukiya Ayase is a gentle, kind-hearted, and innocent university student. His only remaining relative, his cousin Tetsuo, betrays him by selling him to the highest bidder at an auction, hoping to make a huge profit to pay off his debts. Somuku Kanou, a bad-tempered (though very wealthy) loan shark, rescues Ayase and buys him for an impressive 1.2 billion. Kanou apparently knows Ayase from a past incident between them, but Ayase cannot remember who Kanou is nor does he understand why he "saved" him. In a desperate effort to keep Ayase close, Kanou demands the debt be repaid in full and suggests the perfect way to do it: by selling his body to Kanou for 500,000 each time. Ayase is horrified at first, but something soon begins to grow between them that can't be bought for any price.