- "There's one thing I can say for certain. Heroes really do exist. We've just seen one, and now he's coming home."
- ― AWACS Sky Eye
Mobius One is the main character of Ace Combat 04: Shattered Skies, and is arguably one of the most successful aces ever to take to the skies. He was a key figure in helping the Independent State Allied Forces (ISAF) achieving victory in the Usean Continental War, as well as in its efforts against the Free Erusea forces following the war. The total number of air victories achieved by Mobius One is one of the highest ever to be achieved by a single pilot. This is evident in his flawless track record, having never been shot down during a mission, and having risen from the position of rookie to top ace in less than twelve months.
During his ISAF tour of duty, Mobius One flew various aircraft ranging from light interceptors to all-weather, multipurpose, ground atack, and even stealth-capable air superiority fighters. His signature aircraft was the ISAF blue-tinted F-22A Raptor, which remained his choice fighter following the end of the Usean Continental War.
On his first combat mission, Mobius One singlehandedly shot down six Tu-95 Bear bombers, along with their fighter escorts at New Field Island. After that Mobius One continued to perform unbelievably well in combat operations afterwards at a godly and inhuman level. In particular, he is credited for the destruction of the Erusean super-weapons Stonehenge and Megalith. He also is the first pilot to shoot down a member of the world renowned and feared Erusean ace fighter pilot unit known as Yellow Squadron, personally shooting down both Yellow 4 (when that squadron responded to his destruction of Stonehenge) and Yellow 13 (during the Siege of Farbanti). He was the involved in such operations as:
- Operation Rough Seas: A strike role in the sinking of the "Invincible" Aegir Fleet.
- Operation Countdown: One of the defending air superiority pilots of the launch of a key ISAF satellite during the largest air battle since Operation Battle-Axe of the Belkan War, believed to have involved over three hundred aircraft. He made some key achievements, shooting down an SR-71 Blackbird, E-767 AWACS, KC-10A Extender, 6 B-2A Spirit's, and hitting a member of the Yellow Squadron, possibly Yellow 13.
- Operation Bunker Shot: A close air support role during an ISAF amphibious landing on the southern coast of the mainland, allowing them to begin to retake the continent.
- Operation Stone Crusher: A major strike role in the destruction of the superweapon Stonehenge, a turning point in the war, and the death of Yellow 4. This event led to him gaining worldwide fame.
- Operation Fire Fly: A pivotal ace during the eve of the emancipation of San Salvacion, and the destruction of much of the Yellow Squadron, except for Yellow 13, who's plane was damaged by Mobius 1.
- Operation Autumn Thunder: A leading ISAF pilot at the siege and capture of the Erusean capital city Farbanti. The (probable but unconfirmed) death of Yellow 13.
- Operation Judgment Day: A role which is responsible for the destruction of Megalith and the end of the war. He and his squadron also took down the last of the Yellow Squadron in that battle.
Mobius One was a part of the 118th Tactical Fighter Wing through out the entire war, but during Operation Judgment Day the entire squadron officially was renamed Mobius Squadron in honor of him in the squadron's last official mission.
In 2006, he returned to Erusea to defeat the last of the Erusean extremists calling themselves "Free Erusea." Only Mobius One and AWACS Sky Eye were sent, but together they effectively crushed the resistance putting a halt to their operations; after the Usean Continental War it was discovered that Mobius One's combat ability rivaled that of an entire ISAF squadron. During the last battle against free Erusea, Mobius One was engaged by four to six X-02 Wyverns. Despite the technologically more advanced Erusian fighters, he successfully managed to destroy them and afterwords he returned to base safely. There are no records indicating what became of Mobius One after the end of the conflict.
He appears as a boss in Operation Ace of Aces where he appears to be slow, but some time later he will act like the Varcolac Squadron.
- Nothing is known of Mobius One's identity, apart from his callsign and the nickname he earned late into the Usean Continental War. He may be male, given that SkyEye called him "he" or "him" repeatedly at the end of the game.
- Mobius One and Yellow 13's paint schemes are found in most games of the series following AC04. Additionally, he makes a non-canonical appearance as an enemy ace on the Ace Combat Zero bonus mission, The Gauntlet. He only appears on the Ace difficulty and under the condition that the player shoots down Espada Squadron in under one minute.
- Some Erusians called him the "Grim Reaper".
- Mobius Squad Insignia features a squared Mobius Strip
- There is a popular belief that Cipher is Mobius One; that he served in the Belkan War in 1995 and then returned to his native country of USEA to then join the ISAF in the Usean Continental War. Mobius One's appearance in "The Gauntlet" (see second note above) is not canon, so some came to believe that Cipher was fighting his future self, or as others have said, fighting his inner demons. But, Mobius One is mentioned as a rookie pilot in the beginning missions of Ace Combat 04, and not having the legendary reputation or rank of Captain that Cipher did, so it is still a highly debated topic.