Believing they were too similar in "Mega Man X3" (in which Zero could only be played as for part of each level), Capcom wanted Zero to be further distinguished from X for his first appearance as a fully playable character in "Mega Man X4". This resulted in the removal of his Z-Buster (his equivalent of X's X-Buster), leaving only his lightsaber-esque Z-Saber. This close-range combat weapon stood in stark contrast to X's projectile weapons. Due to the difficulty of playing as Zero, the vast majority of the developers were against that decision at first during "Mega Man X4". As a result, Zero was given special techniques (some of which hailed from the "Street Fighter" franchise) by defeating each boss, which resulted in the approval from the developers. In order to make Zero's story to be more engaging, Capcom created Iris, a female Reploid, believing it was a fresh idea not used in previous games in the series.