Chocolate and Mint

Keiko is a junior 2nd year student, but has no experience in love. One day, while going to school, she helped an unconscious 'cute boy' who fainted from anemia. Being 2-faced, he doesn't thank Keiko but instead called her an old lady. Surprising as it is, that boy goes to her school and is a first year.

(Source: Sugar888)

Also contains two one-shots:
Sono Te wo Hanasanai (その手をはなさない, Never Let Go of This Hand)
Sweet na Kankei (SWEETな関係, Sweet Relationship)