Jo Jang-soo is a 20-year-old South Korean soldier and former high school student, known for his quiet strength, loyalty, and emotional intelligence. Raised in a disciplined military household, he's dependable, calm, and selfless—often putting others first. As Class 3-2’s vice president, he plays a key role in their survival after being conscripted during an alien invasion, becoming a steady protector and emotional anchor for his classmates.