Chihaya's proclamation leads to a showdown between Mashima Taichi and the transfer student Arata, who is being shunned by their class.  The stubborn Taichi, who's upset by how close Chihaya and Arata have gotten, steals Arata's glasses in the middle of the tournament.  Arata, good as he may be, is unable to take cards without his glasses.  That is when Chihaya steps in to take his place.
you're no longer allowed 
to play in tournaments.
no tendrías por qué participar en torneos.
no tendrías que participar en torneos.
não participe mais de torneios.