Garakuta no Ai o Hitobanjuu

From Renta!:

Tatsuyuki loves sending in jokes to his favorite radio show, following in the footsteps of legendary fan, "Juliana Saitama." One day, Tatsuyuki professes his love to Juliana over the airwaves. The very next day, though, he finds out Juliana is his boss Mr. Kanii, whom he can't stand!! And, it turns out Mr. Kanii is actually gay…!! He'd meant that confession as a joke, but Juliana's about to take his first time!