This round, as most of the ones you've already completed, takes place in 3-man squads, in Free For All battles. A Rank tournament is, what is pretty obvious, a lot more difficult than the previous ones, that is why it's worthwhile to visit local shops and buy new artifacts. Some of them are insanely expensive (20,000 ryo!), but they give a huge advantage over the enemy.
This round is quite typical - novelties will come with future ones. After completing this round you will be automatically enlisted to preliminary round. You can start it right away, or complete one of the new Ally Events - "The Misplaced Kurosawa", "Difficult Password" and "The Power Behind the Smile". If you want to complete them, go to the "Ninja World Tournament - Ally Events" chapter.