- Reserved, diligent "a-lot-has-happened-since-I-became-a-teacher" Sawa-chan's facade cracks in S2 E10 "Sensei" when people start calling Death Devil "cute" during the wedding performance. She snaps hard enough that the lights in the auditorium go out.
- The first time "My Love Is a Stapler" is played live, Yui forgets to sing. Mio jumps in to take the words. For the shy girl she is, that's pretty awesome. They even turn it into an epic duet.
- The seiyuu actually playing their instruments for "My Love Is a Stapler" and "Fuwa Fuwa Time" in the Let's Go concert.
- And in the Come With Me concert, "Pure Pure Heart" and "U&I" (as well as performing Fuwa Fuwa Time" again).
- The song U&I doubles as a heartwarming moment.
- The encore at the end of Episode 12 definitely counts.
- Yui improvising a whole new verse for Gohan wa Okazu during the movie.
- The concert in the classroom close to the end of The Movie. Once again doubles as a heartwarmer due to the circumstances that lead up to, and even during it.
- The movie's opening has the four girls playing some pretty hardcore metal out of nowhere.
- In S1 E3, the normally airheaded Yui manages to ace her make-up exam after badly flunking it the first time around. Even though she temporarily forgets how to play guitar afterwards, this is the first time that her ability to succeed whenever she put her mind to something becomes apparent.
- In S2 E9, Yui once again passes her exams, but this time does it while she's also practicing a musical act for the local talent show with Azusa. That's pretty impressive for someone who once couldn't focus on academics without sacrificing her guitar skills.
Awesome / K-On!