For every dramatic moment in this series, there are also moments that make you want to cheer.
Kaoru rejecting her Sorority invitation and saying that to Fukiko's face. And two episodes later, mauling Aya and her Girl Posse for bullying her in the middle of class.
And again, when in episode 29 she gives Fukiko a huge What the Hell, Hero? and comes up with the idea of dissolving the Sorority.
Tomoko defending Nanako from bullies in Episode 7. More noticeable and heartwarming because, thanks to Mariko's manipulations, she was mad as Hell because she thought Nanako had abandoned her... but the moment she saw Nanako defenseless, she left that aside and did what she thought it was the right thing.
Later in Episode 29, when Megumi trash-talks Mariko after her suspension, Tomoko splashes her with her drink, initiating a Cat Fight. Though Megumi manages to bitch-slap Tomoko twice, Tomoko keeps fighting unaffected and sends the other girl into the fountain.
Nanako standing up for Junko in Episode 15, and later in Episode 27 willingly leaving the Sorority to support Mariko when she's kicked out of it.
Mariko calling out both of her parents in Episode 28. Overlaps with Tear Jerker.
Rei stopping the very misguided Miyuki and Megumi from burning the sorority petition books under the orders of Ogiwara and Komabayashi. in Episode 30.
In Episode 26, Fukiko tries to stop Nanako from visiting Rei. She tries to trap her in an elevator, orders her around, slaps her, and instead of going home, Nanako calls Fukiko out for her cruel behavior towards Rei.
Nanako: You never do anything for St. Juste-sama!
Komabayashi, of all people, gets one in Episode 31 - spending all of her time as a part of Fukiko's antagonistic Girl Posse, when Owigara has a mental breakdown while interrogating Nanako about her deal with Fukiko, she eventually has Nanako cornered and nearly killed from falling through the old balcony railing. Komabayashi pulls a Big Damn Heroes and dives in, saving Nanako and then bringing Owigara to her senses.
Also, for all of the "weak" and "pushover" accusations from fandom, Nanako has a subtle one as early as Episode 9, when she's capable of saying "no" to Mariko after the infamous birthday party incident. After the failed Murder-Suicide, Mariko comes to school late and sits next to Nanako, taking her hand and trying to apologize. Nanako says nothing and swiftly retires her hand, letting Mariko know that she's angry and for a good reason, and it'll take Mariko quite a bit of time to earn forgiveness. And in that said episode, when she asks Rei for painkillers for a pretty much passed-out Kaoru and Rei replies with all kind of odd phrases, Nanako slaps Rei.
Nanako:"H-how can you laugh in a moment like this?! what's so funny? Our friend is in danger!"
Episode 27: Aya is at it again, antagonizing Mariko about her home life, and Mariko dishes out possibly the nastiest beating she's ever given Aya. In the climax, Aya brings in a magazine display Mariko's father and his mistress to show off to the whole class, and though Mariko tried her damndest to remain composed, it eventually caused her into enter a Tranquil Fury and slash Aya with a box cutter.