I've played my share of RPG maker jam games by now, and one thing that always makes them stand out is custom assets! The original art and music really make this one shine... really great pixel art and illustrations, and the music is well done. The only thing I would have liked to see is more than just tiling floors during the story segments... you see a lot of that, and it does stand out as unfinished looking. But I know this is a prototype, so I imagine that's on the to-do list!
The story was good so far! My only critique there is that the dialogue slightly stilted... but overall it works. I think with another pass to give it a bit more of a natural flow and it'll be perfect!
I did unfortunately hit a crash-point in the web version. When fighting "Boss Rekka" she was invisible, though I could still battle her. But when I defeated her, the game go stuck there... music still running, characters moving, but no ability to do anything or leave the battle. This could be a web-specific issue. If I have the time, I'll try and checkout the download version later!
Overall, what I played so far was great! I hope you are able to keep working on it!