長鴻出版社
The series is licensed for regional language releases in France by Soleil Productions under the English title "Secret Sweetheart", in Spain by Editorial Ivrea, and in Taiwan by Ever Glory Publishing. The original volumes were also imported to the United States and sold as is by Borders and Waldenbooks bookstores in early 2005. In March 2008, to celebrate its 40th anniversary, "Shōjo Comic" posted free chapters of "Boku wa Imōto ni Koi o Suru" on its website, along with a new side-story.