Yotsunoha (よつのは, Yotsunoha? lit. Four-leaf clover) is a Japanese visual novel developed by Haikuo Soft, and was originally released as an erotic game on January 27, 2006 for the PC as a limited edition containing a set of three CD-ROMs in Japan, followed by the regular edition, released on September 1, 2006 as a DVD for the PC. A PlayStation 2 version titled Yotsunoha: A Journey of Sincerity, published by Gadget Soft with adult content removed, was also released on August 28, 2008. The story in Yotsunoha focuses on the appeal of the four female main characters. The gameplay follows a linear plot line, which offers pre-determined scenarios and courses of interaction.
Yotsunoha has since then spawned two spin-off titles, Osananajimi to no Kurashi Kata and Nono to Kuraso, and has made several transitions to other media. A manga adaptation illustrated by Japanese artist Bow Ditama was first serialized in the Megami Magazine on January 30, 2008. It was followed by an original video animation series animated by Hal Film Maker was released on two DVDs on February 29, 2008 and March 28, 2008, containing one episode each. There were also two Drama CDs, and two Internet radio shows hosted by Yui Sakakibara in order to promote the game.