鞘師里保 (Sayashi Riho) is a Japanese dancer and actress. She is a former idol under Hello! Project as a 9th generation member of Morning Musume. and the SATOYAMA movement duo Peaberry. She was the most popular member out of Morning Musume.'s 2011 additions. Starting with "Only you", her second single as a member, she was pushed into becoming one of the group's central figures as a main vocalist and dancer, which led to her being named the group's "absolute ace" (絶対的エース; zettaiteki ace) by media. Sayashi graduated from Morning Musume. at the end of 2015 and took a break from Hello! Project activities to study language and dance abroad. On December 7, 2018, it was announced that her contract with UP-FRONT PROMOTION expired at the end of November 2018 and she had subsequently graduated from Hello! Project. Despite her departure, she made her return to entertainment activities on March 30, 2019 as a guest in Hello! Project's annual Hina Fes concert. In late June 2019, she began performing as a support dancer for the kawaii metal band BABYMETAL.