She's not really a tsun. Her attitude towards him is exactly what you'd expect it to be based on what she thinks of him:
Thinks he's a pain in the ass always showing up and brushing off her attacks: Constantly lashing out at him, but respects him.
Thinks of him as her savior, no idea why he still gets her flustered: Friendly, but easily angered.
Has realized she's in love: Supportive and helpful, doesn't lash out at him even when he gives her reason to.
The definition of a tsundere is literally 'a person who is initially cold or even hostile towards another person before gradually showing a warmer side over time'. If that doesn't describe Biribiri I don't know what does
Yeah no. Being cold but gradually warming up is a kuudere. Though they're cold towards everyone and warms up specifically in regards to the person of their affection.
"The Japanese term tsundere refers to a character who "runs hot and cold", alternating between two distinct moods: tsuntsun (aloof or irritable) and deredere (lovestruck)."
Specifically, a tsundere uses the hostility as a defence measure because of insecurity towards the person she loves. This is a natural reflex for them.
Misaka ceased the hostility once she fell in love, and consciously refrains from showing any irritability at all towards Touma once she realizes it. If anything this order would be the reverse if she were a tsundere.
Clearly we're finding our definitions from different sources. Also you're looking way too far into things. A kuudere does not necessarily act hostile towards someone, just aloof and distant. Classic example: C.C. from Code Geass.
You're also taking tsundere as one specific definition for one specific case. You could compare two different types of tsundere, for example Ayano from Yuru **** and Uryuu from Mirai Nikki, but most people would still class them both as tsundere.
Misaka becoming more friendly once she knew she was in love is a perfect example of a character being hostile, and then showing a warmer side. It's a specific type of tsundere, but it is still tsundere. If you don't regard her as one, then what could you possibly regard her as?
You don't need to continue this argument if you don't want to - it feels like one where we're not going to agree no matter how much logic we throw at each other. I've just made lunch, and am going to go eat while watching some anime, so I won't be continuing.
Next time just link them to the TVTropes article. Not only do they learn they are wrong, there's also the side benefit of trapping them for hours in the seemingly endless hell that is TVTropes.org .
Except apparently he got his definition from TVTropes, which means he's just delusional. Zappy Dan the Magnet Man is one of the best examples of tsundere... ever. She even plays it straight with people who aren't Touma.
There are more evident clues for me being a nerd than that.
Running the anime rec board is once, doing programming and physics is another. Hell, using Funnyjunk in and of itself is evidence that I'm a nerd.
I'm taking my definition from TVTropes. The go-to place for anything trope related.
Misaka becoming friendlier once she realized it has nothing to do with tsundere. August 22nd she fell in love with him after he saved the clones, up until then she actually legitimately disliked him. On August 31st she became conscious of him after overhearing his answer to Etzali on whether he'd protect her, this made her stop being crude towards him. Some time in October she had the love epiphany and realized she loved him, from this point on she actively tries to become part of his life, supporting him in everything no matter who that means would become her enemy.
This is simply called character development. She legitimately disliked him because he pissed her off with his actions and attitude at first. Once that was gone, all there was was a Tomboy gradually acting more feminine until she realizes she's in love, at which point she becomes aggressively supportive.
You get your definition from the TVTropes article on Tsundere, which describes BiriBiri literally to a 'T', and also has her listed in the 'Harsh' category. Your source material disagrees with you.
that loli chick was the sole reason I stopped watching the show after 2 episodes or something. Will she be there through the entire show, because if not I might watch it. Shows premise was really cool, but most loli/moe characters are just so boring I can't stand to watch them anymore.
Hm well I agree with the other guy that Railgun (and the science side of the show in general) is much more interesting than the magic church stuff. Although I still do enjoy the magic church stuff, and I don't dislike Index (loli chick) as a character at all. To be honest, aside from a few arcs, she's kind of just a supporting character who appears more commonly than the others - the story is much more about Touma going around saving damsels in distress by, as the title suggests, punching villains the face. The loli chick appears in about every arc, but again, she's not an important character for most of them.