Ijiranaide, Nagatoro-san

Don't Toy With Me, Miss Nagatoro (イジらないで、長瀞さん, Ijiranaide, Nagatoro-san) is a Japanese webmanga series written and illustrated by Nanashi. An anime adaptation aired in April 2021, directed by Hirokazu Hanai at Telecom Animation Film.

Plot
When an introverted male student meets a girl called Nagatoro, his life is turned upside down. She first quietly observes his reaction to verbal abuse from some other high-school girls that are not well-meaning, realizes that oddly enough in his case it may be exactly what he needs, and so begins a sequence of her teasing him. It soon becomes increasingly obvious (to the reader, not to him) that her teasing is actually sardonic, well-intentioned, and flirtatious, but he eventually starts to catch on.