Onyanko Club
On April 25, 1985, Kokushō made her professional debut as a founding member of Onyanko Club (member #8). Because she had already graduated from high school and was attending college, she was senior to most of the other members of Onyanko Club and became the de facto leader of the group. However, the "public image" leaders of the group were promoted as being Eri Nitta, Miharu Nakajima, Satomi Fukunaga, and Kazuko Utsumi. Kokushō continued to stand out as a leader of the group, however, even with publicity surrounding the solo debut of fellow member Sonoko Kawai.