Got to love the Tsun-tsuns...

One of my favorite character types is the tsundere. What exactly is a tsundere? Well...

"I'll describe this topic... since it figures that you wouldn't know what a Tsundere is. Look, if you really must know, I suppose that I'll tell you. Just... consider yourself lucky that I just happen to have an article handy, o-okay! ^blush
 
Baka.

 ...ahem..." (from Tsundere - Television Tropes and Idioms)

Right...so if you didn't quite get it, tsunderes are characters that run "hot and cold." These characters possess the traits of tsuntsun (aloof or irritable) and deredere (lovestruck). Often times, they go back and forth between these two personalities, usually when a special person is involved.

Ryouko Ookami usually portrays a grumpy pessimism

In any case, my favorite type of character is the Type A Tsundere (the Tsun-tsun). These characters initially start of with a harsh facade to the world. They look strong, independent, and usually have a sort of grumpy pessimism. When in contact with their special person, their mode usually switches to a softer, weaker persona. It is this disparity in their outward self and inward self that I really love.

Natsuno Kirihime, a huge Tsuntsun

Some examples of a Type A Tsundere are Ryouko Ookami from Ookami-san, Motoko Aoyama from Love Hina, Rin Tohsaka from Fate/Stay Night, Asuna from Sword Art Online, and most recently, Natsuno Kirihime from Inu to Hasami wa Tsukaiyou!.