A Japanese actress, born on November 20, 1980, in Setagaya City, Tokyo, Japan. Her works include Perfect Revolution (2017), Sunny: Our Hearts Beat Together (2018), and Rebirth (2011), for which she was nominated for Best Supporting Actress at the Japan Academy Film Prize. She married Wataru Sakata. Koike graduated from Yosawa Elementary School in Setagaya and Kudan Japanese and Western Girls High School.