Osaka mentioned before that she always feels an urge to press buttons she knows she shouldn't press, and when Tomo defends her actions in a dream of hers by saying "When you see a button, you gotta press it, right?" Osaka comments "Ohh, I know how it is."
Osaka found out that she had hay fever a while back, and it was also shown that she also has a very strange way of sneezing. Here, she talks about hay fever and gets a sneezing fit, which amuses Kagura greatly. The fact that Yomi also has it is referenced here too.
Tomo takes advantage of the fact that Chiyo is a fan of the Tokyo Giants by tricking her and saying she has a player's autograph to give her, just because Chiyo didn't want Tomo to attend her party, seeing as she was mad at her. Chiyo's fandom is something we learned of in an earlier chapter.
Kagura talks about how Chiyo's family is rich.
Sakaki says she doesn't know how to make stuffed animals. The reader found out about this when she tried to make plushies for the first cultural festival.
What the policemen were up to, something Osaka and Tomo are very interested in discussing.
When Tomo turned 17 years old.
It is never explained what the other girls were going to give Chiyo for her birthday (besides Sakaki and Kagura).
Tomo freaks everyone out by saying she killed Chiyo-chan, only to offend Chiyo when she does come to school by explaining that it happened in a dream and that she killed Chiyo because otherwise she'd die herself.
Kagura's and Tomo's attempt to figure out what I.T. stands for.
Osaka's and Tomo's theories about policemen.
Chiyo's 12th birthday.
Kagura's and Sakaki's homemade Neco Coneco, unrecognizable to Chiyo.
Yeah, well, I woke up earlier than usual. You see …
… I killed Chiyo-chan.
— Tomo (to Osaka)
Please don't kill me in your dreams!
— Chiyo (to Tomo)
Oh, plus the button right next to it was the one that would kill me! And I couldn't bring myself to press that one, you know.