Eternal Fighter Zero is a 2D doujin fighter developed by Tasofro, better known for developing Immaterial and Missing Power and Touhou Hisoutensoku. The colourful cast of characters are originally from the visual novels Moon, One: Kagayaku Kisetsu e, Kanon, and Air. Many of the characters’ attacks reference other fighting games such as Guilty Gear, King of Fighters, Last Blade, and many more.

EFZ version 2.x. Released by Twilight Frontier on August 2002, during Comic Market 62.

This version added 3 new characters from AIR (Mizusu, Kano, and Minagi), and added UNKNOWN as a hidden playable character, bringing the total number of playable characters to 16. Kanna from AIR was used as the true final boss.