Motoyan Oku-san to Gyaru Musume-chan

The first love of our protagonist, Shouta, is his neighbor Yoshihata Nao, a married woman who was a delinquent back in high school. She's known Shouta since he was a baby and treats him like a little brother.
Having a lazy husband with debts, Nao has to work especially hard to support her family. But lately, she is more worried about her daughter, Yoshihata Natsuhi, who has become a gal and doesn't seem to care about her future. Because of this, Nao asks Shouta to be her daughter's tutor and help Natsuhi with her studies.

While our protagonist tutors Natsuhi—and is regularly teased by her—he realizes that he is still in love with Nao.

Will Shouta confess to Nao despite her being married?
And what is going on with all the teasing from Natsuhi?

A story of a summer love begins.