This one can be really short, and even if you level up your characters (which you don't really need to, especially if you limit yourself to only use the ones that you think you'll want to keep and set the others aside, only using as carriers of medical herbs and perhaps to take a bit) it still is short. Plus each battle is short, so it's a good candidate if you don't have so much time right now, very unlike the vast majority of RPGs.