I just finished the manga the other day so it's still fresh in my mind. I wasn't expecting Hayami Saori as Nanakura but it was a pleasant surprise. She's played a really wide range of characters so it's fun to see her in a role that does... exactly that.
Okay, for the actual Giji Harem: CUTE! They're both just teasing each other throughout the episode. It's really playful and funny at times. Not much else to say yet since we're only establishing the characters.