[Avrorrange]

From the translated information provided at the back page of the seventh volume, it seems to me that volume seven isn't actually a prequel. At the very least, it wouldn't be a pure prequel, it similar to volume four and five, where there were occasional flashbacks. The blurb from volume seven mentioned something about the Princess from the Impostor's interfering in the fight between team scarlet and this other team who challenged team scarlet to a fight.