The four artists are collectively known for performing as a vocal quartet on the song "Itsuka Kitto!" for the anime series Ai no Wakakusa Monogatari, also known as Tales of Little Women or Little Women, which is part of Nippon Animation's World Masterpiece Theater. The song served as the second opening theme for the series, which aired from January to December 1987. Initially featured as an insert song in early episodes, it was upgraded to the opening theme starting with episode fifteen and continued through episode forty-eight, replacing the first opening theme "Wakakusa no Shoutaijou" by Eri Nitta.

The track "Itsuka Kitto!" was performed by Mayumi Shou, Keiko Han, Eiko Yamada, and Rei Sakuma, who provided the voices for the four March sisters Beth, Meg, Jo, and Amy respectively. In the song, each singer performs lyrics that reflect her character's personal dreams for the future. The series alternated between two television-size versions of the song, with one featuring the verses of Meg and Jo and the other featuring the verses of Beth and Amy, depending on which sister was the focus of a given episode.

While these artists are more widely recognized for their extensive voice acting careers, this particular musical collaboration stands as a notable anime theme song credit. Rei Sakuma is additionally known for her singing involvement with the group DoCo, which was formed from the cast of the anime Ranma ½.