@moel A quite simple reason: with the mask on, he's an assassin, but without that mask he's just another average citizen with weird clothing.
Let me elaborate: masks are cool and useful and all that shit, but they really aren't good for going undercover, so if you go outside while wearing such a flashy mask, then you're more likely to be targeted as a suspicious individual, which when coupled with the crime that just happened a few blocks away, makes people go for your ass and remember your description in record time. Without the mask on, he's a weird-ass teen going through the streets late at night, which makes him, while not completely clean, a less likely suspect and lowers the chances of being recognized or people remembering your features.
So you just put the mask on while you're at work and take it off when you finish your work; an assassin enters, a citizen leaves. Sounds kinda stupid but so are people, you'd be surprised by how many people actually get fooled by the domino mask disguise.
As for how I know such stuf... well... let's just say that I know a thing or two, and so do you now.
..........sleep with your doors locked this week. Knowledge has a price.
