"Pop'n Music, most commonly shortened to Pop'n, PM or PNM, is a music video game in Konami's Bemani series. The game is notable for its bright colors, upbeat songs, and cute character graphics. Although Pop'n Music was originally intended to be played by couples on dates, it has greatly escalated in difficulty since early iterations, and has since then attracted many players of beatmania and other Bemani games. Originally released in 1998, the game has had 15 home releases in Japan as well as many arcade versions."
Source: Wikipedia, "Pop'n_Music", available under the CC-BY-SA License.