Velvet Kiss

Velvet Kiss (ベルベット・キス, Berubetto Kisu) is written and illustrated by Chihiro Harumi. It is serialized in Takeshobo's magazine Vitaman since 2009.

Plot
Velvet Kiss is about Nitta Shin, a salary man, who won the lottery. After a one night stand with a prostitute, he signs a contract that gets him into an 80 million yen debt. His creditor has Nitta keep a certain woman "company" in order to pay off the debt.

Other Sources

 * Wikipedia