17sai no Ketsudan (17歳の決断; A 17-Year-Old's Decision) is the first autobiography by Sayashi Riho. It was published on March 26, 2016 by Odyssey Books. The book chronicles her life, from her discovery of her love of dance at age six, her experience auditioning for Morning Musume, and her life as an idol up until her graduation. Aside from an interview and images from her five year career, it also includes exclusive photos taken between her graduation announcement and her graduation concert at Hello! Project COUNTDOWN PARTY 2015 ~GOOD BYE & HELLO!~.