Oresama na Douki ni Yoru no Shigoto ga Baremashita.

Mizuto Kusaka is a serious and diligent office worker... by day. At night, however, he works as a rent-boy! One day, he heads to the club after work as usual, but the client who's waiting for him is, unbelievably, his obnoxious, accomplished coworker Shinichi Takasugi! Shinichi gently caresses Mizuto, who can't help finding it... irresistible... An arrogant hotshot and a goody-goody with a wild side get down 'n' dirty in this steamy office romance!

(Source: Renta!)