I was reading up on the Akiba Culture Zone where it is this morning (after a quick Google). Sounds like an interesting place to take a look so I will be adding it to my list

I also see that there is a RobotRobot store at Nakano Broadway too so I'll probably have a look in that one too when I go there.
I do find it annoying that most of these places don't open until 11am ... means that you have an awkward amount of time to fill before going to them.
Personally I've never attempted a Maid Cafe, (due in part to the probable language barrier) ... I'm tempted to give somewhere like the Goodsmile Cafe a go this time (although I may just chicken out and eat at the UDX building).