Living at Choson Pavilion without the guidance of his father, Prince Sado began getting into trouble. His deviant behavior is said to have started with palace matron Han's suggestion to let the Prince play occasionally so that he could vent his frustrations. The matrons made swords, bows and arrows to play martial games with him. Sado thoroughly enjoyed the games, however he soon began to worry that his parents would find out. Nonetheless, the games soon became an obsession. Several years later when King Yongjo found out, Han was dismissed. At about this time, a barrier began to grow between the father and son.
The year when Prince Sado's behavior became noticeably strange was 1745. He often fell ill and lost consciousness. His illness worsened after the death of his sister Princess Hwap'yong whom he was very close to. Sado returned to his martial games and when he wasn't occupied with his games he painted. He also grew an avid interest for occult texts. He spent a large amount of his time studying and memorizing magic formulas. Thus his studies suffered significantly. King Yongjo would publicly humiliate Sado by testing him on his studies in the presence of many officials by asking one difficult question