Maysa, also known by his alias Commander Beef, is a character from the MegaMan NT Warrior anime series who operates under a dual identity. By day he runs a fish stall in the local market, presenting himself as an eccentric and slightly excitable fish seller who claims to know nothing about NetNavis, PETs, or the cyberworld. In reality, he is a highly capable Net Agent working under the codename Commander Beef, and he secretly operates the NetNavi SharkMan.EXE. His civilian persona is a deliberate act designed to conceal his true work, and he maintains it by acting confused about technology and constantly promoting physical exercise and healthy eating, especially seafood. He frequently reminds others to take their calcium and stay active, believing that young people rely too much on electronics. When he transforms into Commander Beef, his demeanor shifts completely: his voice deepens, he becomes a composed and authoritative leader, and his knowledge of the net and its history becomes evident.

Maysa's motivations stem from his sense of duty as a Net Agent. He works alongside two other agents, Sal and Miyu, to combat cybercrime and protect the network from threats posed by organizations such as World Three. He takes a personal interest in guiding the young protagonist Lan Hikari, often providing strategic advice, Battle Chips, and direct NetBattle support through SharkMan. Although he maintains a tough exterior, he genuinely cares about Lan and his friends, and he serves as a mentor figure during the first season of the series. In addition to his professional responsibilities, Maysa harbors a secret crush on Ms. Mari, which occasionally creates comedic rivalry with Higsby.

Within the story, Maysa plays a recurring role in the original series, frequently appearing to assist Lan in dealing with virus outbreaks and World Three schemes. He participates in the N1 Grand Prix competition, where he battles other NetNavis while deliberately pacing himself to allow Lan time to practice. He also teams up with Lan in tag battles, though SharkMan is sometimes disqualified under unfair circumstances. His secret identity is nearly exposed when Lan deduces that Commander Beef is Maysa, but a quick diversion by Miyu dressed as Maysa preserves the cover. Later, in the episode involving the Life Virus, Maysa aids Lan alongside Higsby and Ms. Mari. In the follow-up series MegaMan NT Warrior Axess, Maysa returns to DenTech City to pursue the criminal Gauss Magnus. During this appearance, his true identity is revealed to Lan, who learns that everyone else already knew the secret. Maysa helps rescue Ms. Mari, who had been mistaken for another person by Gauss. After this episode, he largely disappears from the main storyline, though a parallel world version of him appears in later seasons, and an imposter JammingMan masquerades as him.

Key relationships include his close working bond with fellow Net Agents Sal and Miyu, whom he leads as their superior. He holds deep respect for Lan and becomes a significant ally, often fighting side by side with him. His NetNavi SharkMan is a trusted partner, and the two are known to work effectively together. Maysa's personality is marked by a blend of exaggerated eccentricity in his civilian guise and focused competence as Commander Beef, but this is not a split personality; rather, his civilian behavior is a cover that occasionally bleeds into his agent persona. He possesses strong NetBattle skills and extensive knowledge of the cyberworld, using SharkMan's aquatic-themed abilities to counter viruses and hostile Navis. His dedication to his mission and his protective instincts toward his allies define his development from a seemingly simple fish merchant to a respected covert operative.