This troper always thought it was interesting that although Yui was the main character, it was Ritsu and Mio who restarted the light music club. But then she realized that the foundation of a rock song is the kick DRUM and BASS. It was the drummer and bassist that (re)-founded the light music club! Also, the most important relationship in a rock song is the relationship between the drum and bass. Out of the club, it is Ritsu and Mio who have the strongest and longest-established friendship.
Regarding the dialogue: In the original Japanese version, in Episode 1, Yamanaka says a line that is translated as "Light Music as in Light, not Heavy". This translation causes many fans to wonder how a Speed Metal band (Death Devil) could possibly be allowed to exist in the Light Music Club. However, in the Dub, Yamanaka's explanation is changed slightly to address this issue before it becomes relevant. Instead of the original line, she says "The Light Music Club is about playing light-hearted music". Death Devil's songs, while much heavier and more aggressive than anything Houkago Tea Time ever writes, still have fairly light-hearted lyrics, which means they're still playing light-hearted music, it's just more aggressive.
Additionally, this could also be due to the Japanese music culture. In the West (Europe and America), Heavy Metal is practically a taboo on mainstream radio, but in Japan, Heavy Metal is celebrated to the point where Japanese Pop Music typically draws elements from Heavy Metal. This is why many Metal bands sell so well in Japan. Because the Japanese love Metal. And since the word "Keiongaku", which "Keion" is derived from, literally means "Pop Music" it makes sense that a previous Light Music Club band would play Metal. It also explains why many of HTT's songs are rather heavy by Western standards.
In Episode 9, when Azusa joins the Light Music Club, she is asked to play something for the others, and Azusa says that she's still only a beginner and probably not very good, then proceeds to deliver a mind-blowing performance. Later in the same episode, she says she's been playing since fourth grade, and started because her parents were in a Jazz band. So she's been playing for several years and has parents who both played one of the most difficult genres to play (and in the anime, she even first wanted to join the Jazz Club, but was disappointed with it and joined the Light Music Club instead). All this considered, why does she say "I'm still only a beginner, and probably not very good"? Easy. The answer is Values Dissonance. To Western viewers, Azusa comes across as insecure, possibly even suffering from self-esteem issues, but to Japanese viewers, Azusa is just being polite and respectful, by lowering herself in front of the group she wants to join (who also happen to be her upperclassmen). It's the exact same when Ritsu asks who wants to be the band's Lead Guitarist, and Azusa, despite clearly being the best guitar player in the room, says that she thinks Yui should get that role. Later, when Azusa is officially a part of the Light Music Club, she makes no such self-depreciating remarks, and even considers herself to be at least as good as Yui at guitar.
In Season 2 Episode 3, when Ritsu says she wants to quit playing drums because she's not visible during their performances, she comes across as nothing but an attention-whore. However, in the end, she decides to stick with drums, after reflecting on why she started playing drums to begin with. To any musician, it is obvious what the real problem in the episode was: She didn't actually want attention. She just felt burnt out and needed an excuse to try something else, but in the end realized that she loves playing drums more than anything else (both Ritsu and Mio even point out that Ritsu has never gone a day without practicing, even when she only had the sticks).
It is clearly established that Azusa is the best guitar player in Houkago Tea Time, from the moment she joins the band. So naturally, both Yui, Ritsu and Tsumugi get Azusa to teach them, when Ritsu and Tsumugi are briefly interested in learning to play the guitar. However, none of Azusa's three students ever make any real progress. At first, this might not make sense to most, but it actually goes to prove something that most people get wrong: Just because someone is a great guitar player, it doesn't mean they're a great teacher too. Yui makes a little progress, but that's only because Mio already taught her the basics more than once. The others never learned the basics of how to play a guitar, and thus have no foundation for Azusa to build upon.
Figurines of a tortoise and a rabbit decorate the staircase railing of the main characters' school and at the top of the staircase is their music clubroom. The main characters later adopt a club pet, a turtle. The moral of "The Tortoise and the Hare" is "slow and steady wins the race." HTT's members are extremely lazy and don't take practicing seriously yet always pull off brilliant performances nonetheless.
It never happened but a plot point in the restarted manga is that Azusa is Hollywood Tone-Deaf. However this wouldn't translate as smoothly to the anime, where on a meta-scale she has albums where her voice actress was singing just fine in character.
Who are the other two members of the Occult Studies club? They need a minimum of four right?