18+ Himedore: Hime to Dorei no Gakuen Seikatsu

Naito Fujishiro, high school year one, is really bad with girls. Dodging girl after girl, he's finally managed to enter the boys-only school of his dreams... Or so he thought! Little did he know that the school is becoming a coeducational school from this year!! Having realized this fact only on opening day, Naito stood at a loss right in front of the school gate. It was then that he met the girl nicknamed "The Pure White Princess," Himeka Ichinose...

(Source: Kodansha, translated)