This is going to be a bit disorganized, but we go.
The game looks and sounds really good, but the gameplay could be improved. Much as they were easy, there were a heavy amount of battles, which was a little disruptive in areas that require some exploration to get through and there was not much incentive to find resources (though I get it's kind of a plot relevant the heroes have hoarded all the potions).
I also found some of the maps to feel like confusing wide open spaces. The forest was the worst because it just felt like trees and stones were scattered around at random (you might look at some of the sample maps of forests for ideas). The mazes actually felt a bit less confusing, since having walls did guide me a bit and you're supposed to be a little uncertain in a maze. It was not too bad in town, but adding some paths around town would be more realistic.
A common tip for RPG Maker maps, especially interiors, is to avoid big square, mostly empty maps. The first house I went into with the guys and the chest could have been way smaller, especially since the building itself was pretty small from the outside.
I liked the twist ending. It would be cool if their were two endings (1 where he believes the demon boss and 1 where he does not) depending on how the hero behaved in some situations. Like whether or not he chose to fight or negotiate with the monsters guarding the stairs, and if there were response choices for talking to NPCs where the player could chose between a more forgiving or more hostile response.
Curious how did you do the page turning effect at the beginning. Was it a plugin?
Neat you recolored the MV Logo, though it is actually possible to turn if off -- it's triggered by a plugin that's on by default. Finally, one of my favorite plugins is the keyboard options plugin, because it allows players to add WASD and any other keys to the controls if they wish: http://www.yanfly.moe/wiki/Keyboard_Config_(YEP)