A few thoughts
Of course, the first thing I want to say is that I really enjoyed the game. It was a lot of fun. It was frustrating sometimes but overall very satisfying to play.
The animation and sound was excellent. Forcing the player to watch the stance of their opponent and learn about their combos was brilliant. It really adds tension to the game.
I will offer my thoughts on some things you may consider if you indulge us and make a sequel.
First, I would have liked to be able to skip the tutorial. I've started several new games and had to sit through it every time.
Next, I am wondering about the level system. Is there a difference between putting points into health and into guard? If damage is subtracted the same between both bars, then it seems like there's no reason to favor health or guard, as they are the same thing. I also didn't like to sacrifice my level points for the combos. I felt like all the combos should be learned separately and kept forever.
I would prefer, I think, to level up damage and defense, in addition to guard. You could also add special skills, like a hint as to where they will strike, the ability to move twice, the ability to suppress the enemy's super gauge, or to enhance your own, to start the match with some of the gauge filled already, or even add different gauges like some of the later street fighter games. You could have another skill that lets you counterattack if you block every strike perfectly with a simple three-strike combo or something.
I think it would be a little more fun if you had some kind of timed bar, so that when you block, you can block perfectly and reduce the damage taken, and the same with the strike. I think it would add a little more variation to the gameplay, and make it feel a little less like a pure numbers game.
Finally, I want to say that your game is a pleasure to play and I hope you work on more of them.