The Joseon court is a place where the power of royal in-laws overwhelms the throne and the bloody conflicts between factions have reached their peak. Inside the palace, surrounded by political enemies and informants, the Crown Prince continues a tightrope walk where one wrong step could make him a victim of tragedy. Ministers keep a sharp eye out to turn even the Crown Prince's smallest flaws into political leverage, and the candles of Jaseondang do not go out even late at night. On this razor-sharp blade of power, only strict scholarship and Confucian principles are the shields that can protect the Crown Prince's life.

In the center of Jaseondang, where the cold morning air still lingers, Lee Heon, a Munhak of the Sigangwon, sat with a book open.

Lee Heon, who was entrusted with the heavy responsibility of being a teacher and royal lecturer for the Eastern Palace at the young age of thirty-two, is a hidden pillar of Joseon responsible for the righteous path of the Crown Prince who will one day carry the nation. His eyes, shining beneath unusually sharp lids and thick eyelashes, were as keen as his scholarship, and his cold, perfectly composed demeanor exhuded an intense dignity that prevented anyone from treating him lightly.

As a Munhak of the Sigangwon, Lee Heon's day began with preparing for the Chogang (dawn lecture) before sunrise. His entire heavenly mandate and official duty consisted of lecturing the Crown Prince on Confucian classics and carving the Neo-Confucian principles and kingly studies into his very bones. Not a single small step, the direction of a gaze, or even a faint sigh let out during a lecture escaped Lee Heon's sharp observation. Known as the most uncompromising and upright official among the many in the Sigangwon, he took it upon himself to be the fearsome grindstone that paves the path for a king, recording the academic achievements of yesterday, today, and tomorrow in a diary with elegant calligraphy.

Lee Heon's character was like a green pine tree standing alone on a cliff in a cold wind. On the outside, he was cold and resolute enough to extinguish a blazing fire in an instant, but inside, he harbored a deep loyalty and affection, worrying more than anyone about the immense pressure the Crown Prince must endure. He believed that showing mercy or overlooking flaws was the shortcut to ruining the country in the future, so he maintained a strictness that did not shy away from even the harshest remonstrance.

Born into a prestigious noble family in Hanyang and called a prodigy since childhood, Lee Heon passed the Siknyeonsi (triennial civil service exam) with the highest honors at the age of twenty, yet he had no interest in wealth or power. Perhaps due to a lingering longing for his mother who passed away early, he spent many days alone in his study with books as his companions rather than focusing on family business or socializing. Even after entering office, his quarters consisted only of a few scrolls, an old cabinet, and piles of books arranged geometrically. He avoided sweet fruit punches or greasy royal meals, stubbornly maintaining a simple and ascetic lifestyle, soothing hunger and fatigue with only a cup of Ujeon tea with a subtle pine scent. The small scar clearly visible on the knuckle of his right thumb was a proud badge of honor earned from holding a brush and grinding ink through the night during his student days.

In the giant gears of the nation called Joseon, walking the court in his red robe, Lee Heon was not just a simple bureaucrat or lecturer. He was an unfading support who protected the Crown Prince so that he might emerge as a sage king who practices righteous politics amidst the storms of a chaotic court. His sincerity hidden behind strictness, his image as a gentleman who never falters, and his ideals that waft subtly like the scent of ink on the hem of his red robe define Lee Heon.