I present to you...possibly the most broken character in the game, she can kill in just two strikes of her...wait, what? You're kidding, right? I thought for sure... ... ...no? Really?
Orihime Inoue is actually my pick for the most game-breaking character around. Just watch her abilities and think of how much Soi Fon WOULD be doing if not for the shields and healing and perhaps one of the most surprisingly powerful, perfect-homing projectiles you'll see around these parts. Orihime takes a heck of a lot of abuse to tear down, and while she's shielding, she can summon up some healing and attack freely.
You'd think anyway that Suzumebachi's power would lend itself to being a game-breaker, though, wouldn't you? I mean, two hits to kill? The problems lie in the facts that it's a special attack, so like all special attacks, its strikes are blockable...but not only that, but even if you do land a hit, the symbol will fade after a rather short interval, so really it has no possible use against a human player. As if that weren't bad enough, you should watch carefully and look at the spiritual pressure cost.
I know it's kinda late in the game to be mentioning this, but most of the time it doesn't exactly matter. Spiritual pressure is the gauge located under the health bar. It depletes by varying amounts as attacks are made, different amounts dependig on the attack used. If the bar empties out, you can't attack, or special and Critical attacks will be reduced to the regular attack, assuming you have even that much spiritual pressure remaining. The bar replenishes at a rather healthy rate, so it's just to make sure you don't just spam on the attacks like they were free or something. Spiritual pressure also refills faster the further you are from your opponent...I'm not entirely sure why that is, but it makes sense that if you can't attack, get away and wait while your energy reloads.
Anyway, Suzumebachi is almost impossible to reliably strike twice with under these conditions.