Know what I'd do?
First: Put the plug up to the Remiu's mamumamu. The piss combined with electricity will probably fry the thing in a painful death in a matter of seconds.
Second? After the Marisia is gawking over her sister's terrible death, I'll rip up her hat, throw her and the fried Remiu outside (or find their parents) and proceed to watch the ensuing drama.
First: Put the plug up to the Remiu's mamumamu.
Actually upon reflection I realize the plug wouldn't do much since it's not connected to an electrical socket. So I'd probably just need a copper wire and some heavy-duty rubber gloves.