Koharu Kusumi (久住小春, Kusumi Koharu, born July 15, 1992 in Niigata Prefecture) is a Japanese actress, model, television personality, and singer. In 2005, she became the only seventh generation member of the Japanese idol girl group Morning Musume, a part of Hello! Project.

While Kusumi was in Morning Musume, she provided the voice for Kirari Tsukishima, the main character of the anime series Kirarin Revolution, and portrayed her in real life on Oha Suta. In addition, she was featured in several musical releases affiliated with the series, including both solo releases under the name Kirari Tsukishima starring Koharu Kusumi (Morning Musume) (月島きらりstarring久住小春(モーニング娘。)) and group releases for the units Kira Pika and Milky Way.

After leaving Morning Musume in 2009, Kusumi pursued modeling, discussing her career changes in her 2011 autobiography, 17-sai no Tenshoku. After making her runway debut in 2011, she modeled exclusively for magazines CanCam and Steady, while also making regular appearances on variety shows. At the same time, Kusumi continued to perform at music events and took part in Dream Morning Musume. Kusumi also ventured into acting, appearing in shows such as Woman Prisoner 7 and Doctor-X: Surgeon Michiko Daimon.