From which episode did the expression of shock come from?

The sixth episode of "Five-point Flower Marriage", the story of this episode is quite interesting, especially one flower and three nine. At the end of the last episode, Yihua saw that her sister Sanjiu liked Fengtaro, but in this episode, Yihua took out the demeanor of a big sister and framed her sister Sanjiu and Fengtaro.

Nakano Sanjiu is one of the heroines in the comic book Bride of the Five Teachers and its derivative works, and the third daughter of the five sisters of Nakano.