This story takes place in Percy Jackson's world, however you need to note a few things:

Most importantly, most of the events of the fourth book, Battle of the Labyrinth, did not happen. Percy and co didn't go on the quest into the labyrinth, therefore they didn't meet Daedalus, and therefore he didn't die. However, he is still their sword master, only Quintus is his last name, as nobody knows his first name.

The war with Kronos is over. There is no war happening at the time this story takes place. However the world is still ravaged with monsters who came back to avenge their old masters.

Also, I have made up a new goddess called Neoma for this story. You will find out a bit about Neoma in the story.