Kobato-chan has a penchant for running out of bathrooms naked (and crying). How many times does this make after this episode?
I thought she was hilarious as well when she went bananas over Kate supposedly being "another imouto". Maria's pretty well-behaved (and with more manners) when in Kodaka's presence though; Kate should take some cues from him regarding how to deal with her sister.
Kate's unusually crude mannerisms make her an instant standout character in my opinion, especially since she's unabashedly displaying them and her very mature personality (apart from her stalking tendencies regarding Maria) adds to that as well.
The others had a time to shine, especially with the way they sent/worded their messages to Kodaka, and his tsukkomi to each and every one was a nice reminder as to how he is the most normal and well-adjusted character in the land of nutcases.
The girls looked stunning (Yozora as well, but before her change to a
black tracksuit, of all things) in their casual outfits.