First Love Sisters (初恋姉妹, Hatsukoi Shimai) is a manga originally created by Mako Komao with original art designs by Reine Hibiki, and illustrated by Mizuo Shinonome which was first serialized in the now-defunct yuri josei manga magazine Yuri Shimai on June 28, 2003 under the title Koi Shimai (恋姉妹). The manga was transferred to Comic Yuri Hime, Yuri Shimai's successor, published by Ichijinsha. The final chapter was published in the eleventh issue of Comic Yuri Hime, and three bound volumes have been released, with the final one on April 18, 2008. The manga has been licensed by Los Angeles-based company Seven Seas Entertainment and the first volume went on sale in January 2008, but the series is now on hold due to rights issues. Three drama CDs based on this series have been released, the first two under the title Koi Shimai and the third under the title Hatsukoi Shimai.
During a visit to Tsunojo Girls' Academy, Chika Matsuzato meets the girl of her dreams, cool upperclassman Haruna Kizaki. Even though they spent only one short day together, Chika will never forget Haruna's kindness, and has made it her life's goal to study hard and get accepted into Tsunojo Girls' School so that they can be together. However, things do not go as smoothly as Chika had planned when she finally arrives.