It was a nice bit of tickling, but it seemed to finnish on a sad note. I wish someone could explain what happened.
Don't worry -- it's not sad, just typical Japanese melodrama
Blonde girl (Chitose): Hey! Kawai!
Dark-haired guy (Kai/Kawai): What now? Here to mess things up AGAIN?
Chitose: Pin Asai Mugi's arms!
Kawai and Mugi: Huh?
Chitose: Hurry up and do it!
Mugi: Kawai! Chitose?
Chitose: Prepare yourself, Asai Mugi!
Light-haired guy: Give it a rest, you guys!
Brunette girl (to guy): Wait.
Chitose: Here goes! .... (tickling starts) Koochy koochy koo ```
Purple-haired girl: What's she trying to do??
Brunette: Well, there are two advantages to laughing. One is that, by relaxing, her nervousness will disappear. The other one...
Mugi: Chitose! Stop! Stop
stop!
Chitose: Not yet!
Mugi: What are you doing, Chitose?!
Brunette: ... is
that.
They then proceed to ramble a lot about Mugi having a good voice, and how Chitose is going to be in a performance in May (and Mugi too). Apparently it's some sort of drama performance. The melodrama at the end was just the brunette gushing over Mugi's fine voice