Seriously, not a comment and not properly tagged? Time to change that! It's a ZUN© drawing after all

But I doubt this is Marisa.. maybe just a random maid

Clearly not Marisa. I wondered if this was VIVIT but apparently not her either (wrong hair color).

Guys, are you serious? Its the hat that tell you who the character is!

This is Maribel.

ZUN said:
I drew a maid. Why? Because.
I had an image of a maid calling "Hello." from within the confines of a darkened room. (No, I'm not kidding.)
Despite that, the atmosphere seems comparatively liberated.
Yes, a dark picture. (^^;
The fact that you cannot even tell in what time period this is supposed to be is like me.
But anyway, I wonder if this maid is doing her job. (Hint: She isn't.)

And why is it tagged as touhou? Yes, it's Zun, but is doesn't make it Touhou...