We can see this contrast of passive and active most clearly in the late s2 episode where Tsumugi and Ritsu first hang out alone together. The episode begins with Ricchan calling up Mio to do something fun together, which Mio refuses because she has to study for finals. Ricchan also knows that Yui is studying with Nodokachan and is unavailable. She meets Mugi by chance and tells her she was about to ask her next. Mugi's eyes light up and she immediately cancels whatever other plans she had alone in order to spend time with Ritsu, as this is the first time they will be do something together privately. (Now, as a sidebar, we can take a quick glance into why Mugi was only Ritsu's third choice. It makes sense that the two of them are the most distant from eachother emotionally out of the group. Ritsu and Mio were childhood friends and Ritsu shares more in common with Yui, due to their inherently active personalities. And everybody loves Azunyan, obviously.) Now, this episode is very important for them as it brings them closer together, but we can take a closer look and see their opposing personalities complete eachother. Mugichan immediately hands the reigns over to Ricchan and tells her that she wants to do whatever Ricchan decides. We then see Ricchan take the active role and lead her through many experiences She's never had before, from arcades to candy shops, Ritsu teaches Mugi how to enjoy the very simple things. She even wins Mugi a stuffed animal at a crane game! What luck! I digress. As the story comes to a close, we learn of Mugi's desire to be bonked on the head. This is, infact, her trying to break a little bit out of her passive nature. She mentions that she longs to have a more physical connection with the others, who are able to express their affections in such active ways.