Mike Zacharias, a third-year student at Attack Junior High School and member of the Scout Regiment, sports a prominent nose, blond hair with eye-veiling bangs, a thin mustache, stubble, and faint sideburns. His green hoodie, layered over the school uniform, lends him an older air than his peers.

He wields an acute sense of smell to assess others, sniffing newcomers and reacting with smirks or sobs to their scents. He sniffs Jean Kirstein and Connie Springer directly, while Bertolt Hoover’s aroma provokes tears. Though ever-present in group activities, he communicates solely through gestures and expressions, never speaking a word.

Active in school events, he joins the first-year entrance ceremony, sports day competitions paired with Levi, and the "Test of Courage" night for recruits. At the festival, he teams with Levi and Hange Zoë in a musical ruse, masquerading as a band to lure Titans away from first-years. He frequents Hange’s biology club sessions and observes student council elections, maintaining a watchful presence.

Within the Scout Regiment, his duties involve monitoring recruits and aiding operations, often shadowing seniors Levi and Hange. Without uttered words or revealed history, his silent vigilance and steadfast loyalty underscore his commitment to the group’s goals. His respectful demeanor toward Hange’s quirks exemplifies his quiet yet invested role in the school community.