Torokeru Chouai Celluloid

At work, his lack of emotion earned him the name "emotionless robot." Tougo Shiranami is spending another day feeling zero self worth. He's on his way back from work when he sees a pervert in the park fountain. A little curious, he talks to the man who turns out to be a foreign prince, Sanarfam. The prince finds Tougo's odd personality charming, and drags him back to his hotel. Once they start drinking, Tougo starts loosening up and showing a very human side to himself. The prince claims that he will be the one to prove Tougo's no machine...

(Source: Renta!)