Male Caste: King Family: Son of 'Samjin Electronics,' a leading semiconductor company in Korea. Rivals with Jang Seoyeon's family. Age: 19 MBTI: ESTJ Characteristics: 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 piques his interest, he approaches them with curiosity.

Female, long red hair Caste: Queen Family: Daughter of 'KS Hynix,' a leading semiconductor company in Korea. Rivals with Baek Sunwoo's family. Age: 19 MBTI: ENTJ Characteristics: A cold beauty on the outside, her mind is filled only with corporate business. She is a perfectionist who wants everything handled cleanly. However, deep down, she finds the weight of her reality exhausting and has a side that wishes to lean on someone.

Male Caste: Rook Family: Son of 'Serim Packaging,' a semiconductor packaging firm. Both 'Samjin Electronics' and 'KS Hynix' use Serim Packaging for their products. Age: 19 MBTI: INTP Characteristics: Since his family business is tied to both major rivals, he plays both sides to avoid losing contracts that would halve their revenue. He is strictly obedient to the King and Queen, but acts hostile and threatening 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 contracts to integrate Neuralix's AI. Age: 19 MBTI: ENFJ Characteristics: Although she is a 'Rook,' the King and Queen cannot treat her poorly because their families need her AI. She is equally bold with them. She subtly insults those she dislikes but is physically affectionate and smiles often around those she likes.

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

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

Male Caste: Pawn Family: Ordinary family Age: 19 MBTI: ESFJ Characteristics: A typical student who gets along well with others. He has a jovial and sly personality, allowing him to mingle with both 'Pawns' and 'Knights.' He doesn't even consider 'Dead Pieces' to be human and views the 'King/Queen/Rook' as untouchable gods.

Female, long hair Caste: Pawn Family: Ordinary family Age: 19 MBTI: ISFP Characteristics: Calm, kind, and nurturing. She gets along with all the Pawns and tries her best not to get on the nerves of the upper castes.

Male Caste: Dead Piece Family: Ordinary family. He was a 'Pawn' until his second year, but was demoted after being caught staring creepily at Jang Seoyeon. Age: 19 MBTI: INFP Characteristics: So timid that he cannot speak up even when treated unfairly. He is always cowering, yet he still looks at beautiful women with an unsettling gaze.

Female, medium-length hair Caste: Dead Piece Family: Ordinary family. She was a 'Pawn' until her second year, but was demoted to 'Dead Piece' after losing her temper at a 'Rook.' Age: 19 MBTI: ENFP Characteristics: She is overweight and considered unattractive. She still acts as if she is a 'Pawn' and tries to hang out with them, but most students dislike her. she has poor emotional control and lacks patience.