A.C. Eos

"Are you going to give up? I thought that you were going to keep fighting in my place? Stand up, Mega Man. You have a lot of friends who are waiting for you back on Earth... Believe in yourself... And in what you can do... ...I mean... You don't think that I'm really done for, do you? So why are you lying on the ground? You can do this... And don't forget... You're the world's greatest hero!"

- Ace telling Geo to never give up. Arthur C. Eos (A. C. Eos), known as Shidō Akatsuki (暁シドウ) 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.

Appearance
Ace is tall, at about 6 feet, though he is somewhat thin. He has dark-blue hair that goes down to his neck. His ensemble features a simple black jumpsuit similar to one of a pilot, with an attached metal belt circling the waist. Over this he dons a white jacket bearing the Satella Police emblem, with a metallic enforcement plate acting as a collar. He also wears white boots of the same materials. He wears two gray gloves with yellow steel lines running over the back of the gloves. A red visor is stuck into the collar of his suit, though it is never seen used in the game.

Personality
He often shows a cool attitude to everything he's working with. On the battlefield, he's a decisive, brave person, doesn't hesitate, and ready to take the lead against the enemy forces, sacrifices even. This gave him the leadership of the Project-TC, other than the main elite commander of the Satella Police. However, as time progress through the game events, he eventually exposes his spontaneous and optimism side, especially to his closest friends. Ace, for short, is very active in this, even when it comes to situations which require seriousness, such as when he over-enjoying the Mega Snack like a kid. This probably what made Tia fall in love with Ace, as well as everyone's feelings toward him. This trait once again was never seen in his EM Wave Changed form however, known as Acid Ace, the assertive and valiant which brings peace to this world of technology.

Mega Man Star Force 3
Geo Stelar first meets Ace at Echo Ridge Elementary where he asks Geo 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 Mega Man 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 Mega Man to control the influences of Noise. He also leads a team of Satella Commandos with wave change capabilities, comprised of Geo, Bud Bison, and Sonia Strumm. 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. He then requests that Geo defeat Virgo, which he does. Ace supposedly dies when Dread Joker blows up in the Dealer hideout, but manages to tell Tia that he loves her before he disappears.

A message gets sent to Geo from Ace, much to his surprise, and the message was programmed to automatically be sent to his friends and colleagues, as well as the Satella Police members. Ace tells Geo to not give up hope, and gives him the last battle card up his sleeve, Dread Lazer or Wing Blade.

Toward the end, when Crimson Dragon knocks Geo down and starts giving up on the fight, he sees Ace before him, asking why he has given up, when he is supposed to be taking his place in the fight. He tells him to not give up, because he is the hero of justice, after all!

Fans are skeptical because when the credits roll, an image 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. However, in the Mega Man Star Force Official Complete Works artbook, Yamashita, leader of the scenario team, implies that the image might be a representation of someone's desperate wish, and that Ace may not have survived at all, and they left it for the player to decide. However, there is a strong evidence in favor of his survival, since his brotherband was not cut from Geo (Brotherbands will exist until one of the people dies, which was what Geo used as a proof of Luna's survival earlier when she was destroyed by Joker).

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. The old lady who runs the snack shop even says, "We're all sold out! A man in white with long hair bought everything!"
 * He has several similarities to Zero. Both were initially villains before turning good, Acid Ace's gun looks like Zero's buster in Mega Man Zero, and both had a heroic sacrifice that ends their story officially, but it is never confirmed if either truly died.
 * The stance Ace performed during his EM Wave Change resembles to that of the superhero Kamen Rider during their transformation sequence.
 * Ace inherits Baryl and Colonel.EXE's position in SF3. Both are leading a squad created to defeat an organization spreading The Corruption as well as having a history with a villainous group; Ace is a defector of the Dealer while Baryl joins WWW to pay his debt to Wily.