Arthur C. Eos (A. C. Eos), known as Akatsuki Shidō (暁シドウ Akatsuki Shidō?) in Japan and often referred to by the nickname Ace, is the deuteragonist of Mega Man Star Force 3. Ace is a Satella Police Commandos officer that can EM Wave Change with his Wizard, Acid, to become Acid Ace. The two are registered under the Satella Police's Project TC as No. 001. He is the creator of the Hunter-VG, which allows Wizards to materialize. Due to Acid being a man-made Wizard and not a natural EM Being, his EM Wave Change puts a tremendous strain on Ace's body to the point where Acid will voluntarily revert the transformation in order to protect Ace.