Another brain fart

I'm looking for a manga. Yaoi between a writer or artist of some sort and their assistant maybe . . . The seme is the writer and he is straight to begin with but the uke is gay and he is in love with the seme. One day the uke hears strange noises coming from the semes room and catches them jacking off with a fake vaginal tube thing and the uke comes in and asks if he can help . . . After helping the seme jack-off with the toy he runs off with it saying he's gonna clean it off but instead he uses it to jack-off later on . . . It would be super if someone could help me out with this (〜￣△￣)〜