Very impressive game!
But it has a lot of minuses in it. The length of the game is sadly a reason that breaks the perfect score, it seems almost impossible to finish in one day due to petty monotonic gameplay. Thank god there are at least different enemys from time to time and several hidden items to break this complete monotonic curse. Another minus would be the price miscalculations that highers the price of gear significantly for every stat increase.
Overall this just cuts of half a star. The other half is beacuse I was really expecting a boss battle with the demon, instead there's just a small chat scene and *SPOILER ALERT* the end.
As for what are those 4 stars for is definitely for solid art graphics, smooth gameplay and a good upgrade collection.