I still don't get why these two have a student x teacher tag when Rikka (I'm assuming that older woman is Rikka) is a doctor. Negom made it clear that she's a doctor in her doujin..
Am I the only one that pronounces Mercedes' name like the car brand? Also, Am I also the only that, since I pronounce the name the same way as the car brand, I keep thinking to the Raisins girl of the same name from South Park?