Sensei, Ore ni Kamawazu Itte Kudasai!!※オナニーしながら描きました♥ Are You Gonna Come? Drawing While Masturbating Onanii Shinagara Kakimashita 先生、俺にかまわずイッてください!!

Can't find any info on this manga so please make do with this makeshift description: A god tier manga assistant is currently looking for a job. Luckily, one of his fellow classmates from university happens to have a sister, who also just so happens to be a serialised manga author. Man, these coincidences just keep getting stranger since he walks in on her while she was doing the thing in the title.