Gessekai

{{Infobox song

| name = Gessekai (月世界)

| cover =

| alt =

| type = single

| artist = Buck-Tick

| album =

| released = May 13, 1998

| recorded = 1997

| studio =

| venue =

| genre = Rock

| length = 16:06

| label = Mercury Records

| writer = Atsushi Sakurai, Hisashi Imai

| producer =

| prev_title = Sasayaki

| prev_year = 1998

| next_title = Bran-New Lover

| next_year = 1999

}}

"Gessekai" (月世界) (English: Moon World) is the fifteenth single released by the Japanese rock band Buck-Tick, released on May 13, 1998.{{Cite web|url=http://www.cduniverse.com/search/xx/music/pid/2063802/a/Gessekai.htm|title = Buck-Tick - Gessekai CD Album}} The song "Gessekai" was used as opening theme of the anime Nightwalker: The Midnight Detective.{{cite web|url=https://www.jame-world.com/en/article/118860-buck-tick.html|title=Buck-Tick|date=26 April 2013 |publisher=JAME|accessdate=2022-05-08}} Track three is a remix of "Muchi no Namida" from Sexy Stream Liner done by Tomoyasu Hotei.