Haru o Matsukoro (1979)

Chizumi is a clumsy and innocent young girl, who had just started living on her own after her older sister get married and moved out. She still goes to high school and is fortunate enough to have two close friends, but her life started to change when Fujiomi, a classmater of hers helped her to retrieve a hat that was given by her sister but was accidently swept by the wind to the river. Fujiomi is a quiet student, whose strength and calmness are often misinterpreted and brings him into fights with delinquents. When Chizumi wanted to thank him personally, she met the troublemakers and were scolded by Fujiomi for landing herself in trouble. From then on however, Fujiomi couldn’t help himself but to try his best to protect her from harm and the mistakes that she often makes out of her clumsiness. Though it may seem weird to others, Fujiomi’s protective nature and Chizumi’s simple but gentle character allow them to love one another and help those who are around them.

Source: www.anisearch.com/manga/2014