A floating letter magically appears in front of you.
That was an abrupt start.
It would probably make sense to have a bit more description around it, like whether this sort of thing is common in this world.
I was interested to note just how far the game let me go without reading the letter. 
Congratulations!
You have been enrolled to Kibou Mahou Gakuen, a prestigious academy where talented individuals can cultivate their unique talents, in the hopes of one day be enlisted as one of the prestigious Enforcers!
The world is filled with vicious creatures of magical potential as well as criminals and outlaws that threaten the peace of this world.
You are currently at Pluotia, the land where this school reside in.
Note: Students should head to the academy to receive their student handbook and apply for the interview.
This doesnāt feel as though it makes very much sense. Given my cousinās comments, it sounds like this is the sort of thing one would expect to get, so a lot of the explanations feel unnecessary if this is the actual text of the letter. If, however, this is just the narrative explaining the academy, then it probably needs a bit more explanation than that. For one thing, where in Pluotia are we compared to the academy?
You pause for a moment, the term reminded you of your 16th birthday last week. You almost forgot about it.
You write down your age on the paper.
Is there any point to the age choice, given that weāre set to 16, and the game will refuse to accept any other value?
āI know you just moved here, but if you donāt like it you can always just move to the dormitory at the school. I hear itās real nice there.ā
Okay, so am I staying with Rey while Iām at the academy?
So does that mean that I didnāt even know if I was accepted until I got there?
āWell, you should get some rest, tomorrowās the interview session for new students right?ā
So, thereās an interview even after acceptance? Is it even possible to get into this school?
Uncle - (Reyās Daddy)
This should already be obvious⦠Also, when did he leave the letter there? If it was while I was sleeping, surely Iādāve seen it before, and if not, he could have just said it to me.
All in all, while this is a good start, I have to agree with @Megus: thereās a lot of stuff you need to explain in more detail. Say that weāve just moved across the country to the academyās city (even before weāve been accepted), and are now living with our uncle and cousin, and so on.