It's a Tsubasa chapter! She really does well with Ouji's brother - it's just their second meeting, and they're already buddies. (Granted, Ouji's brother might be just doing this just to try and score some brownie points for his brother even though Ouji isn't really into her - but the thought is still there.)
I definitely like Tsubasa as a character - she's cute, and she's appearing more than just a typical tomboy or "I'm friends with everyone" character - it feels like she's becoming more than just a side character. And it makes her just all the more popular.