Ishiguro Aya was a runner-up in a 1997 contest to find a new female rock idol. After the contest was over—with the winner being Michiyo Heike—music producer, former rock musician, and contest judge Tsunku decided to focus his attention on five runners-up, which included Ishiguro, Abe Natsumi, Iida Kaori, Fukuda Asuka, and Nakazawa Yuko. Tsunku promised to take the quintet under his wing if they sold 50,000 copies of their CD "Ai no Tane" (also known as Morning Musume's 0th single) within five days. They accomplished this task within four days, and Tsunku upheld his end of the bargain.