Go back to New Year's Eve and take note of her reference to multiple flags being burned that night. Or to the first LINE chapter and her eagerness to shoo Anna away from Kyou. Or her obvious glee during filming when Anna lost her phone and Icchi couldn't contact her directly. Or her laying a guilt trip on Icchi after the night Anna stayed over. Or, most obviously, the sweets making lesson. She's been low-key after him most of the run and Anna's been on it all the way.
I disagree. Sekine Moeko lives a quite free-style, and likes to date people like Nanjou-senpai; and she is sensitive about feeling and she cares alot about her friend Yamada. Since the 4th grade, to the chapter 1, until chapter 24, Sekine and Ichi don't have any interaction at all.
Chapter 24:
While choosing group for observation, when Kanzaki were chosen to Yamada group, Yamada leer to Ichi, Ichi said:
Ah, I'll grant that you more or less have the authority to discusstings but, that doesn't...
Sekine: Whoa! You can talk!
Then Ichi said too much about choosing group based on interlectiual level and pissed them all off...
At the start, to Sekine, Ichi is invisible (she hates the idea of Yamada befriending with Ichi probably)
Or to the first LINE chapter and her eagerness to shoo Anna away from Kyou
Later on, thanks to Yamada and Ichi relationship, and Sekine cares about Yamada, result in Sekine regconize Ichi as a friend of a friend, and finally, a friend. (she is a bit of regretful to help Ichi in compensate of her flags with Nanjou-senpai being burned)
Go back to New Year's Eve and take note of her reference to multiple flags being burned that night
Her action towards Yamada and Ichi couple is variery from being helpful
Or, most obviously, the sweets making lesson
to just want to make fun of them. (She laughs thinking Ichi and Yamada are fighting)
Or her obvious glee during filming when Anna lost her phone and Icchi couldn't contact her directly.