Bocchi no Boku ni Kyousei Kanojo ga Yattekita

On my 24th birthday, I came home to find a woman who wanted to be my girlfriend! I, a "loner" since junior high school, was confused because I didn't understand what she meant, but she was actually a junior employee of my mother's company, and my mother had asked her to be my girlfriend! Refusal would make my mother sad and make things awkward for her at work. And so a pseudo-romance will begin between two people with ulterior motives!

(Source: Houbunsha, translated)