I did like the action sequences and edited side view battlers - very nice touches! Unfortunately, I didn't like much else about the game. Fun fact: the VisuStella Options Core plugin comes with a setting for random encounters! I turned off the random encounters and went through the game and still found the game rather grindy (I fought all of the on-screen encounters) and the end boss was impossible. Others have already said this, but just to reinforce the point: the cutscenes are too long, regardless of whether the game is a demo or a full release.
Since this is supposed to be a battle-oriented game, a lot of work needs to be done to get the game feeling right. I recommend stripping down the cutscenes and add in more playable sections. Battle balance also needs to be reviewed, since it takes 2 full turns from the player characters to defeat a zombie in the best of circumstances, while the zombies can defeat a player character in 2 hits. While this may sound equal at first, trust me, it's not; the zombies are taking 8 hits to be defeated, while the players are only taking 2 hits. It's not balanced. Also, the end boss is a total bullet sponge and needs to be redesigned completely. There are better ways to design an end boss besides giving them maximum HP and defense.
Game jams are all about learning, so I hope you find the feedback here enlightening. I think you can make an excellent game, just keep improving your skills!