This is far and away my favorite one-on-one fighting game. While technique and strategy are indeed required if you want to get really good at it, there's no need to burn the midnight oil studying move lists or practicing combos; you can jump right into the fray and reap immediate enjoyment. The controls are perfect; the game feels fast and fresh and truly stands apart from the many 16-bit-era Street Fighter II clones. The soundtrack is great, very energetic and exciting, and two-player mode is a blast.
I know many people will write Asuka off based on the assumption that a fighter featuring high-school girls can't possibly be a quality product, but they might find themselves surprised if they simply give the game a shot. It's not "naughty"; the character designs emphasize wackiness and distinctiveness over cuteness or sexiness, and all of the girls have neat techniques at their disposal. Even if you aren't into fighting games (I'm not a huge fan of them, myself), you should give this one a try.
Titular Asuka is Karina's main rival. I bet that if the two were to team up, they'd be able to take down Ryu and Ken, no problem.