The two songs in the single were composed by Hideki Aoki and the arrangement was done by Kabuki Rocks and Nobuhiko Sato. Ichiban Arimura wrote the lyrics for the first track while Hideki Aoki did them for the second one. The second track, "Suicide Game", was used as the theme song for the 1990 Japanese horror fantasy film 1990 Botan Toro.
The single got the 17th position in Oricon's single's chart at the time of its release and appeared in the chart nine more times, achieving a total of 270,000 copies sold.
The mini CD was released on 5 February 1991 by Apollon Incorporated, catalog number APDA-29 and JAN 4988015033885, along with a cassette tape version, catalog number APSA-29. The cassette version includes karaoke versions of both songs.
- "Niji no Miyako" (虹の都) [second ending for Dragon Quest]; 4:23
- "Suicide Game" (スーサイド・ゲーム) [theme song for 1990 Botan Toro]; 4:25