This seems like it's the first chapter where Enji being a robot has a significant role in the story. In earlier chapters, aside from a few blink-and-you'll-miss-it shots of Enji plugging wires into her arm, you could almost forget Enji was an android.
Maa-chan looks a lot like Nobue Itou from Ichigo Mashimaro. She seems to have a somewhat similar personality as well although Maa-chan seems to be a little more responsible than Nobue, who often gets drunk in front of the younger girls.