Curious Case of the Demon Princess

There once was an epic battle that decided a conflict that's lasted for years, a knightly magical girl defeated her nemesis, the Demon Queen, for good. The Demon Queen abandoned her villainous persona and the magical girl finally worked up the courage to ask out her best friend... That happened over 20 years ago.

A sixteen year old 'boy' finds the world changing around them as their best friend is revealed to be a magical girl, and they start realizing their parents are more than they seem... What will be the consequences of the resurfaced conflicts and interpersonal drama when our main character starts to find clues that they may have some sort of mysterious power of their own?