I need help, please

So my friend was looking for something specific. It's a Black and white bl, probably Japanese, and featured a modern setting. Blonde(or light, really) haired dude is the assistant to a darker haired guy. The darker haired guy knew him from before he became an assistent. The dark haired dude is really intent on getting the ml, blondie, to fall in love with him. Throughout the story, though, there was this gimmick of "33 days until he falls in love" like, every chapter or so. Updating as it goes along. Any ideas as to what it could be?