Kamichu!

Yurie Hitotsubashi was just an average middle school student living in the city of Onomichi on Japan's inland sea in the easygoing times of the 1980s. She spent her days worrying about exams and trying to get Kenji, the clueless boy she likes, to notice her. Then during lunch one day she suddenly announces to her friend Mitsue that the night before she had become a goddess. (myanimelist.net)