Kōfukuron
is the debut single by Japanese singer Ringo Sheena and it was released on May 27, 1998 by Toshiba EMI, East World. Since Sheena suddenly gained popularity, it was decided that this single was resold as a 12 cm single. New edition, including the new song, was re-released with the fourth single "Honnō" on October 27, 1999. The 1999 edition was certified gold by the RIAJ for 200,000 copies shipped to stores. Background "Kōfukuron" and "Suberidai" were produced by Hiroshi Kitashiro, who is an audio engineer and synthesizer programmer, and "Toki ga Bōsō Suru" was produced by Uni Inoue, who is an audio engineer and multi-instrumentalist. Seiji Kameda arranged all songs. Sheena wanted to release not "Kōfukuron" but B-side song "Suberidai" as a title tune. However, she gave up on the idea because of opposition from EMI staff. Since Sheena was not pleased with the arrangement of "Kōfukuron," the single version was not included in the album. The song was used as the theme song to the TBS variety show Ai no Hinadan, and the "Etsuraku-hen" version featured on Muzai Moratorium, in a 1999 commercial for Suntory's The Cocktail Bar Cassis & Orange. The song was covered as a part