Cactus's Secret (サボテンの秘密, Saboten no Himitsu) 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.
Miku Yamada has been in love with Kyohei Fujioka since middle school. She tried so hard to become pretty and finally got close enough to Kyohei. The problem is that Kyohei is a clueless, dense guy who doesn't know what love is! She always tries to show him how she really feels, but fails. Kyohei even calls her a "cactus alien" for being prickly to him, but Miku has her reasons. Kyohei just doesn't get it! Will Kyohei ever find out about Miku's true feelings?!