Ai is an Ignis. His real name is currently unknown, but the nickname "Ai" was given to him by Fujiki Yusaku and Kusanagi Shoichi. As an Ignis, he has free will and is sought after by SOL Technologies and the Knights of Hanoi. He currently resides inside Yusaku's Duel Disk after the latter captured him.

(Source: Yu-Gi-Oh! Wikia)