This was pretty fun, but i feel like it would work a lot better if bullies only took 1 hit, or maybe starting bullies took 1 hit while later ones could take 2. Because of this, I always ended up being forced to take a hit at the start. Also, this would probably feel a lot better to play if you could pick up stones if they hit walls, since when I accidentally did that, it was hard to face the bullies with only 1 stone.
The art was great! It felt like the player was actually in a school, and the pixel art clearly represented everything.