My thoughts on this episode is that it is a nice build up to the play with a nice focus on the two suitors for Touko. But two introductions as well, the return of Touko's parents and the new character of Nara sensei.
The father I see as another character in need of healing/redemption from the past or (hopefully not) someone to find Yuu and Nanami kissing to provoke more typical yuri drama.
Is Nara sensei pointing to a new path post the festival, maybe this not the only time this play is performed?
Maybe I am reading two much into this, but in the past Nakatani sensei does not introduce characters for no reason.