Melissa is portrayed as a skilled and battle-hardened soldier with a blunt, straightforward personality. Though highly proficient in piloting Arm Slaves, she favors fast and aggressive combat tactics over precise control, often relying on forceful maneuvers and heavy firearms. While she later pilots Arm Slaves less frequently, she remains an effective operator, though not at the same level as specialists such as Sousuke Sagara or Kurz Weber. Outside of combat, she is multilingual, speaking both English and fluent Cantonese, the latter stemming from time spent in Hong Kong.

Melissa’s off-duty persona is marked by her rough humor, heavy drinking, and abrasive manner of speech. She is known to smoke heavily and drink to excess, at one point leaving numerous empty beer cans scattered across Teletha Testarossa’s coffee table. Her crass language and tendency to insult others often make her appear abrasive, though it underscores her tough, no-nonsense background as a former U.S. Marine. She also maintains a casual relationship with her younger boyfriend, Tashiro, who is comically noted for being attracted to her legs.

Despite her harshness, Melissa often plays the role of a mentor and stabilizing force for her teammates. She trains Sousuke in verbal discipline, inspiring his use of aggressive drill-sergeant language, and is capable of practical jokes, particularly when teasing him about Tessa Testarossa’s feelings. While she frequently mocks her comrades, she also shows a protective and loyal side, balancing her rough edges with moments of camaraderie and responsibility.

Melissa Mao is portrayed as a tall and athletic woman, reflecting her background as a soldier and former Marine. Her build emphasizes her strength and combat training, while still retaining a feminine presence that is occasionally noted by her peers.

As a member of Mithril, she is most frequently seen wearing the standard sage-green Mithril uniform with combat boots while stationed aboard the Tuatha de Danaan. In the field, she is equipped with tactical gear appropriate for piloting Arm Slaves or ground combat missions. Off-duty, she is sometimes depicted in more casual attire, though her military bearing and confident posture remain consistent regardless of dress.

Melissa Mao was born on May 11, 1976, in New York City to Chinese-American parents. Raised under strict traditional values, she was expected to enter an arranged marriage. Rejecting this path, she fled from home on her wedding day and immediately enlisted in the United States Marine Corps, still dressed in her gown. During her time in the Marines, she gained extensive military experience but was eventually issued a dishonorable discharge.

After leaving the service, Melissa lived in Hong Kong then still under British rule where she stayed with relatives on her mother’s side. Her estrangement from her father, a former U.S. Air Force officer, remained a source of bitterness throughout her life.

Melissa was later recruited by Mithril, an international anti-terrorist organization, where she was assigned the callsign Uruz 2 by Gail McAllen. Initially placed in command of her own team, her unit suffered heavy losses after two subordinates were permanently injured in action. As a result, she was tasked with selecting replacements at Mithril’s secret training camp in Berutarube.

During the recruitment trials, Melissa dismissed Kurz Weber due to his womanizing behavior and poor demonstration of marksmanship, while Sousuke Sagara was overlooked for his low test scores and unremarkable performance. However, during a simulated Arm Slave battle, Sousuke impressed Melissa by defeating a top recruit in an Rk-92 Savage, while Kurz later revealed his hidden sharpshooting talent during a live mission. Following a successful operation to rescue the Belizean president’s kidnapped daughter from communist guerrillas, Melissa recognized their abilities and accepted both Sousuke and Kurz into her squad.

As part of Mithril’s Special Response Team (SRT) aboard the Tuatha de Danaan, Melissa played a central role in field operations, including missions in Tokyo to protect Kaname Chidori. Near the conclusion of the first series, she was wounded in combat against Gauron during an Arm Slave battle at a U.S. chemical weapons facility on Berildaobu Island. Despite her injuries, she managed to aid Kurz Weber in killing Guen Bien Bo by using concealed scalpels, revealing a skill that had not previously been shown.

Melissa developed a close friendship with Teletha “Tessa” Testarossa, giving her informal access to the captain’s office, and maintained longstanding ties with Gail McAllen and Belfangan Clouseau, both of whom later rose to commanding positions within Mithril.

Following the devastating losses suffered by Mithril’s forces during the defense of Merida Island, Melissa rose to the position of second-in-command of the SRT, reflecting both her experience and leadership within the organization.

Sousuke Sagara
Melissa acts as both a mentor and comrade to Sousuke. While she frequently scolds him for his rigid and overly militaristic behavior, she also supports his development as a soldier and helps him adjust to more ordinary social situations. She takes on a protective, almost older-sister-like role, though she does not hesitate to tease him, particularly about his growing bond with Kaname Chidori.

Kurz Weber
Melissa’s relationship with Kurz is marked by frequent clashes due to his womanizing tendencies and inappropriate remarks, which often target her directly. Despite her irritation, she acknowledges his skill as a sniper and ultimately respects him as a teammate. Their dynamic balances hostility with camaraderie, serving as one of the more comedic relationships within the Special Response Team.

Teletha “Tessa” Testarossa
Melissa is close friends with Captain Testarossa, often providing her with candid advice and moral support. Their friendship grants Melissa informal access to Tessa’s office, underscoring the trust between them. At times, she also acts as a grounding figure for Tessa, particularly when the young captain struggles with the burdens of command.

Kaname Chidori
Although not as directly involved with Kaname as Sousuke is, Melissa shows respect for her and occasionally offers guidance or lighthearted commentary on her relationship with Sousuke. Melissa’s teasing often serves to highlight Kaname’s feelings, though she demonstrates genuine concern for Kaname’s safety during missions.

Melissa Mao is recognized within the Full Metal Panic! franchise as a character who embodies the balance between professionalism and irreverence. As a veteran soldier and former Marine, she brings authority and experience to Mithril’s Special Response Team, often serving as the voice of reason between the seriousness of Sousuke Sagara and the carefreeness of Kurz Weber. Her sharp wit, abrasive humor, and practical jokes provide comic relief, while her resilience and leadership highlight the personal costs of war.

Among fans, Mao is remembered as one of the series’ strongest female characters portrayed as both competent in combat and unafraid to show her flaws. Her background, which combines cultural expectations, rebellion against tradition, and eventual rise to second-in-command of the SRT, contributes to her image as a character defined by independence and perseverance. Her close friendship with Teletha Testarossa further underscores her role as a stabilizing figure aboard the Tuatha de Danaan, cementing her importance within the ensemble cast.