A.C. Eos

Arthur Christopher Eos (A. C. Eos), known as Shidō Akatsuki (暁シドウ) in Japan and often referred to by the nickname Ace, is a Satella Police Commandos officer. As one of Geo and Omega-Xis's allies, he can be fought. He 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 Hunter VG, the device that succeeds Transers and Star Carriers as well as allowing Wizards materialize.

Due to Acid being a man-made Wizard and not a natural EM Being, wave changing puts a tremendous strain on Ace's body to the point where Acid will voluntarily revert the wave change in order to protect Ace.

MegaMan Star Force 3
Geo Stelar first meet Ace during the events of MegaMan Starforce 3 at Echo Ridge Elementary where he asks him to enter a tournament being held at Spica Mall. Geo is late to the tournament that Ace won in a couple of seconds. During the events of the game, A.C. Eos teams up with MegaMan and his friends to attempt to thwart Dealer's plans for world conquest. He provides Geo with the Ace Program or Joker Program (depending on game version) to allow MegaMan to control the influences of Noise. Later in the game, it is hinted and then completely revealed that he used to be a member of Dealer before leaving and joining the Satella Police. In the past, it seems that he used to have a romantic relationship with Queen Tia.

During the Dealer attack on WAZA, he defends the base and then fights against Queen Virgo. Virgo gains the upper hand early but Ace turns the battle against her. However, his Wave Change is canceled because of the strain on his body. Then he requests for Geo to defeat Virgo, which is his wish.

He supposedly dies when Dread Joker blows up in the Dealers' hideout, but manages to tell Tia that he loves her before he disappears. Fans are skeptical because when the credits roll, a picture of Ace can be seen in a hospital, being taken care of by Dr. Goodall and Queen Tia, suggesting they found data frags of him and reassembled him and Acid like they did with Luna.

English
Dr. Goodall often refers to A.C. Eos as Arthur, implying that to be his first name. His C. initial is presumed to be Christopher, but this is yet to be confirmed, making his full name Arthur Christopher Eos. In Greek mythology, Eos is a titan and the goddess of the dawn.

A.C. Eos' initials spell the word Ace, which is often used as his nickname, and is a direct reference to the playing card of the same name. Ace is also a term used for someone of great skill in things such as sports or shooting.

Japanese
Akatsuki means dawn.

Trivia

 * After trying a Mega Snack, A.C. Eos becomes very fond of them. He is seen throughout the game munching on one or several whenever he has time to do so, to the point that it worries Acid. They can even be found under his desk.
 * Ace is implied to be deleted by Joker, but in the credits he is seen in a hospital bed, eating mega snacks (with a fork...)
 * Eos could be a reference to the greek letter "sigma". It can contain three symbols that look like this: Σσς.