Ouji to Kotori

Poor art school student Suzuki Keiichi wakes up one day to find himself as part of an auction in some desert land he knows nothing about as a way to pay off his debts. He has no idea what's happened to him until he's suddenly bought by a man he's never seen in a language he doesn't understand. He's terrified, and it turns out the man is a prince who bought him to be the servant of his younger brother. Every day he plots a way to escape from this unknown land, but he finds himself slowly captivated by the prince's charms.

Yamanaka Hiko's hit tankoubon. Book also contains an unrelated oneshot "Sabishisa no Nedan".