This is Book 3 of the Third Keys sega and This focus on Matthew and his point of view and these events is between Apollo and Jeremy story but this explanation on why Matthew had gone to another world and what is this new power that he has inside of him but before all that he must learn about where he is at and figure out how to get back to where he was before traveling to this unknown place.
Also, the art isn't my but if someone says anything then I will keep it up and that also goes for Book 2 too.