Professor Frank, called the "Dueling Counselor," is a competitor in the Fortune Cup who Duels Ruka in a consolation game. Frank is easily recognizable due to his catch phrase, "sa", which he says three times. "Sa" is a Japanese word to request somebody. He is the Yliaster member that Godwin inserted into the tournament.
His first match is unseen, but it is mentioned that he lost to Kodo on purpose, specifically so he could be in the consolation game. In the duel, he hypnotizes Ruka, then enters a trance that allows him access to the Duel Spirit Dimension (specifically, the Ancient Forest). His mere presence appears to be able to destroy the forest. As such, the forest's guardian, Ancient Fairy Dragon, attempts to kill him to save its home; Ruka ends the duel in a draw to save him.
Following the duel, Frank succeeds in his mission, but his mind is apparently wiped.