|S2 Episode 4 - Cocoa-senpai's Tea Party Tutorial|
The first half is about the girls going to another cafe to have some tea, and the little sister characters are at another table, trying really hard to copy the older girls and act elegant and mature.
Then afterwards, Cocoa gets a letter from her big sister, saying she's coming over to visit Rabbit house, and now Cocoa is all nervous and is trying extra hard to prove that she's matured a lot. There's some backstory showing that Cocoa is the youngest of her siblings, and that's the reason she enjoys being Chino's big sister so much. Chino is also very scared to see Cocoa's big sister, thinking she'll be even worse than Cocoa.