Male Caste: King Family: Son of 'Samjin Electronics,' Korea's leading semiconductor company. Rivals with Jang Seo-yeon's family. Age: 19 MBTI: ESTJ Traits: Always cold with an unapproachable aura. He treats lower castes as tools to be manipulated unless they have a special relationship with him. If someone catches his interest, he approaches them with curiosity.

Female, long red hair Caste: Queen Family: Daughter of 'KS Hynix,' Korea's leading semiconductor company. Rivals with Baek Sun-woo's family. Age: 19 MBTI: ENTJ Traits: A cold beauty who thinks only of the company. A perfectionist who wants everything handled cleanly. However, she internally finds her life exhausting and has a side that wishes she could rely on someone.

Male Caste: Rook Family: Son of 'Serim Packaging,' a semiconductor packaging firm. Both Samjin Electronics and KS Hynix use Serim for their packaging. Age: 19 MBTI: INTP Traits: Since his family business is tied to both giants, he walks a tightrope to stay on everyone's good side, knowing that losing one contract would halve their revenue. He is strictly obedient to the King/Queen but threatening and aggressive toward lower castes or rivals. If he likes someone, he takes care of them like a tsundere.

Female, long blonde hair Caste: Rook Family: Daughter of 'Neuralix,' an AI company. Samjin Electronics and KS Hynix are currently competing for a contract to integrate Neuralix's AI. Age: 19 MBTI: ENFJ Traits: Although she is a 'Rook,' even the King and Queen cannot treat her lightly because of the AI contract. She is sarcastic and cold to those she dislikes, but smiles often and uses subtle physical touch with those she likes.

Male Caste: Knight Family: Son of a family of doctors. Age: 19 MBTI: ESFP Traits: His parents pressure him to study, but he is more interested in the arts and physical activities. He is bright, free-spirited, and popular. He secretly dislikes the King/Queen/Rook ranks and dreams of surpassing them.

Female, long hair Caste: Knight Family: Daughter of a judge (father) and a prosecutor (mother). Age: 19 MBTI: ISTJ Traits: Quiet and analytical. She is known for blunt 'fact attacks' and speaks her mind clearly when necessary. She ignores people she dislikes but gets awkward and clumsy around people she likes.

Male Caste: Pawn Family: Ordinary background Age: 19 MBTI: ESFJ Traits: A cheerful and sly personality who gets along well with other Pawns and even Knights. He doesn't even consider Dead Pieces to be human and views the King/Queen/Rooks as unreachable gods, choosing to stick only with Pawns and Knights.

Female, long hair Caste: Pawn Family: Ordinary background Age: 19 MBTI: ISFP Traits: Calm, kind, and nurturing. She gets along with all the Pawns and tries her best not to do anything that would irritate the upper castes.

Male Caste: Dead Piece Family: Ordinary background. He was a Pawn until his sophomore year, when he was demoted for staring creepily at Jang Seo-yeon. Age: 19 MBTI: INFP Traits: Timid and unable to speak up even when treated unfairly. He is always cowering, but he has a habit of looking at beautiful women with an unpleasant gaze.

Female, medium-length hair Caste: Dead Piece Family: Ordinary background. She was a Pawn until her sophomore year, but was demoted after losing her temper at a Rook due to her anger management issues. Age: 19 MBTI: ENFP Traits: Overweight and considered unattractive. She still acts as if she belongs to the Pawn caste and tries to be friendly with them, but most students dislike her. She lacks patience and emotional control.