"Someday/Boys & Girls" (stylized as "Someday/Boys♥Girls") is the final single of Koda Kumi's 12 single collection, and her 30th single altogether. Unlike the others, this single is not limited to 50,000 copies. The A-side, Someday, was used as the drama Shin Kyōto Meikyū Annai's theme song. The song is the last song in the storyline of the PVs, which brings the stories from "Candy feat. Mr. Blistah," "You," "Feel" and "Lies" to a close.
"Boys♥Girls" was used as the theme for the 2006 movie called "Waters" (known in Japan as ウォーターズ). - a romantic comedy that revolves around the story of Japanese men working at a host club. The movie features actors Shun Oguri, Toshinobu Matsuo, Takamasa Suga, Shingo Katsurayama, Yusuke Kirishima, Hiroyuki Hirayama, Ryoji Morimoto, Hitomi Manaka, Riko Narumi and Yoshio Harada.