Zigzix placed several D-Sensors around the Kaiba Dome to measure the Ener-D levels during the Duels of the Fortune Cup tournament. During Leo's Duel with Greiger, Zigzix thought the D-Sensors were broken as they weren't picking up any Ener-D levels (as they thought Leo was Luna), but after increasing the signals that the D-Sensors emit, he managed to trace Luna in the stands. The strong frequency caused Luna immense headaches. During Akiza Izinski's Duel with Commander Koda, the D-Sensors confirmed her identity as a Signer.