17sai no Tenshoku

17sai no Tenshoku (17歳の転職; A 17-Year-Old's Career Change) is Kusumi Koharu's first essay book. It was published on February 10, 2011 by UP-FRONT BOOKS and marketed by Wani Books.

Kusumi talks about leaving her rural hometown of Washima in Niigata Prefecture to join Morning Musume at 12 years old, then deciding to graduate at 17 to change her career. She also discusses her hidden personality as a health nerd and her interest in agriculture.