Sakamaki Akimu manga
Nakamura Kouta is a freshman in high school who dislikes girls. One day he is visited by his childhood friend Karen, with whom he lost contact over time. Karen is a tomboyish girl, who refers to herself as "Boku" (a first person pronoun usually used by males). She asks him to help her become more feminine to win the affection of Itsuki-san, a colleague at her part time job. Even though he is reluctant at first, he more or less voluntarily agrees to help her out in the end. But making a lady out of the clumsy Karen with nothing but his extensive galge experience as reference proves more difficult than he could imagine.