Which Hana?

Hana Kisugi is a somewhat apathetic 28-year-old office worker with no luck at work or with men. One day, she misses a step on a staircase and...wakes up in the body of a 17-year-old high school student named Hana Yamada! At a loss, she ends up living the life of a high school girl but why are so many high-school boys confessing to her?? Will this Hana be able to return to her former body?!