Cactus's Secret is a Japanese shōjo manga series written and illustrated by Nana Haruta. The series began serialization in Ribon magazine on December 29, 2003, and ended its run on April 30, 2005. The individual chapters were collected into four tankōbon volumes by Shueisha; the first on August 11, 2004, and the final on October 14, 2005. The series has been licensed by Viz Media for an English-language North American release as part of their Shojo Beat imprint.

Ribon is a monthly Japanese shōjo manga magazine published by Shueisha on the third of each month. First issued in August 1955, its rivals are Nakayoshi and Ciao. It is one of the best-selling shōjo manga magazines, having sold over 590 million copies since 1978. Its circulation was in the millions between 1987 and 2001, peaking at 2.3 million in 1994. In 2009, the magazine's circulation was 274,167. In 2010, the circulation dropped to 243,334.