The Brat I Hadn't Seen in 10 Years Turned into a Pure, Beautiful High School Girl.

Isamu Arizuki finally quit his job at a black company and he is ready make a fresh start in his hometown, after returning for the first time in 10 years. There, a beautiful but mysterious JK comes into his parents' coffee shop, and she asks him to guess her name, to his consternation… So who are you really…? This is a romantic comedy that recalls the happy days youth from 10 years ago!

(Source: Overlap, translated)