When I started playing Grim Grimoire, I was ignorant of the story. All I knew was that the game was pretty and it was an RTS. By the end of the game's intro, I knew that the game was based in a world where magic exists. I also saw a lot of similarities between the game and Harry Potter. To name off a few:
-Grim Grimoire takes place in a magic school where talented student come to study magic.
-Harry Potter goes to Hogwarts school of magic where young men and women study to become wizards and witches.
-Grim Grimoire has a less-than-popular teacher who's actually a devil. He's like Professor Snape's younger, more perverted brother.
-Professor Snape is only liked by students of Slithering. Other students and teacher tend to stay away from him.
– Dumbledore and Gammel Dore. They look alike, have similar names and both of them are headmasters or magic schools.
-Lillet Blan is new to magic, but is eager to learn.
-Harry Potter is new to magic, but eager to learn.
-Margarita, one of the first girls Lillet meets, is a bit bookish.
-Hermoine Granger is definitely on the nerdy side.
-The first Harry Potter book focused on finding the philosopher's stone. (It's called the Sorcerer's Stone in the US).
-Philosopher's Stone in Grim Grimoire plays an important role to the story.
-Elves are a familiar in Grim Grimoire that you summon out of a rune to do menial tasks such as collecting mana from crystals and tagging behind other familiars and healing them.
-House Elves in Harry Potter are slaves to their master and must do whatever their masters tells them to do or else they end up physically punishing and abusing themselves.
-One character in Grim Grimoire makes a side comment about being burned at the stake or something by regular humans.
-Young wizards and witches aren't allowed to use magic outside in the world of muggles and the older ones who are must exercise extreme discretion.
Those are just a few of the similarities between the magic world of Grim Grimoire and Harry Potter. While the story in Grim Grimoire seemed to parallel that of Harry Potter at times, the two are different enough where it's not hard to separate the two. It's almost as if Grim Grimoire and Harry Potter are two different stories, but existing in the same world.