Zakira Fua is an evil duelist and the main antagonist of both Shori and Shobu, and is also the one controlling Yuu Fua (his younger sister) from the start of the series.

In the Versus Revolution, he reappears in Katta Kirifuda's time, who is Shori's son and Shobu's younger brother, through Basara and the card he uses in the past. However, he only appears as an image of himself in there. (Which is not shown in the Duel Masters Charge, Duel Masters Fighting Edge and Star Cross manga, the three manga series where Zakira does his operations in Shobu's time and exists as a plot hole.)

He is the leader of the Fua Duelists. He is marked as (Z) and ranked as 1st in the organization.

(Source: Duel Masters Wiki)