Zero.exe is a veteran navi from SciLabs, created when Yuichiro was rather young. He's seen a number of years combating viruses and rogue net navi's on the internet, along with aiding in keeping Yuichiro out of trouble. With time, he's retired from netbattling but that hasn't stopped him from training. Nowadays he's content to train Megaman.exe and act as a surrogate parent to him in Yuichiro's stead. When Hub died, it broke his heart to see Yuichiro be so upset.

Much like his other counterparts, Zero has his temper, but is also always ready for a battle and is a very calm individual over all. It takes a lot to rattle him. (This one, is a bit more open to interpretation, since there are a lot of variations on how Zero is played.)