Harold Katori is the 20-year-old First Lieutenant serving as pilot and navigator aboard the United Planets Space Force destroyer Soyokaze. He maintains a consistently calm and well-mannered demeanor, coupled with significant confidence in his piloting and navigation skills; this confidence is evident in his ability to adeptly maneuver large vehicles even under enemy fire. Katori frequently incorporates Buddhist sayings into his speech and meditates during his spare time.

He developed trust in Captain Tylor earlier than most Soyokaze crew members and typically follows orders without question. His peaceful nature fosters positive relationships throughout the crew. Notably, female crew members usually exclude him from their criticisms of male colleagues and actively include him in gossip sessions.

A defining physical trait, revealed in the series finale, is Katori's baldness, which he conceals by wearing a blonde wig.