Something clicked in my head after the end of this episode; flashback to two episodes ago, I knew something was up when they showed that Riko didn't like 'sequels'. See? There's no such thing as a normal nice girl anymore in Anime- everyone of them is either a yandere or a tsundere... This is why we can't have anything nice.
Riko = Lupin I didn't see coming, not that I even knew who Lupin was in the first place... But Aria = Holmes is pretty much in your face from the begining, like the OP didn't leave enough clues... Btw, is there a particular reason why Riko's twintails can do...
That
?