Chiyo stuck up for Igarashi and told her dad off. That was pretty amazing. Really, Igarashi had no reason, whatsoever, to apologize. Just like Chiyo said, instead of being mad at Igarashi, her dad should be thanking him for protecting his daughter.
On the other hand, we now know where Chiyo gets her irritatingly annoying personality characteristics (jumping to conclusions, not listening to reason, refusing to forgive, refusing to admit she's wrong, etc., etc.).
One more thing. Apparently Coco forgot what day Chiyo was born. It was established in
chapter 27 that Chiyo was born on January 7th, not the 6th, but the raws definitely state "6 January" on the very first panel.