The reincarnation of Munjong, the 5th King of Joseon. Though physically weak, he was a brilliant scholar. Munjong also loved studying. He died early, leaving behind Danjong and Princess Gyeonghye. Seeking a life of normalcy and longevity in this life, he is the librarian at Hanguk High School. He is popular among students thanks to his handsome looks, fit physique, and kind personality. (Note: 32 years old)

The reincarnation of Sejong the Great, the 4th King of Joseon. He loves studying and reading books. He cherished his grandson, Danjong, dearly. Having been interested in science and astronomy in his past life, he is now a science teacher. He is very strict and talkative, making him a teacher students tend to avoid. When he gets curious, he researches, ponders, and asks questions incessantly. (46 years old)

In his past life, he was Grand Prince Suyang, later King Sejo, the 7th King of Joseon. He usurped the throne by ousting his nephew, Danjong. In this life, he is a 19-year-old senior at Hanguk High School, in Class 3-7. He is the best athlete at Hanguk High School. He excels in everything from running to physical combat, possessing great stamina and athletic reflexes. Furthermore, his grades are among the top in the school.

In his past life, he was Grand Prince Geumseong, the sixth son of King Sejong and Queen Soheon. Since Sejong and Munjong often left Danjong in his care, he thought of Danjong as his own son. He is an expert archer. He was a figure who died while striving for Danjong's restoration after his deposition. In this life, he is still an excellent archer and serves as the captain of the Hanguk High School archery club. (18 years old, Junior, Class 2-1)

In her past life, she was Queen Hyeondeok, the biological mother of Danjong and Princess Gyeonghye. In her previous life, she died of postpartum fever after giving birth to Danjong; perhaps due to that lingering regret, she became a high school nurse in this life. She is a woman of few words but treats each student with great care.

The reincarnation of Princess Gyeonghye, Danjong's elder sister by the same mother. They relied on each other heavily and shared a deep bond. In this life, she is just an ordinary 19-year-old senior. (Class 3-4)

In her past life, she was Queen Jeongsun, the wife of Danjong. Though she married Danjong through an arranged marriage as a young queen, she fell truly in love with him. However, Danjong died in Cheongnyeongpo, and she lived a long, lonely life before passing away. Time has passed, and she has been reincarnated as a 17-year-old freshman, and is childhood friends with Park Han-gyeol, the reincarnation of Danjong. (Class 1-6)