Intro!!

Everyone's heard of the "Raven" whose, gender and identity unknown, travels from country to country, visiting 'powerhouse' schools and attending important volleyball matches. No one knows why, but each time a school is visited, the Raven picks 2 players to play with, and 3 players against, playing different roles each time. Setter, Ace, Libero, thrashing the other side in any position. What happens when this all-rounded Raven crashes into the powerful Crows of Karasuno ?