One year later, following his father who ascended the throne under General Yi Seong-gye's command after deposed King Chang, Jeongseong then became the Crown Prince (왕세자; 王世子).
[1] In 1390, Seoyeon was opened, a "Sabu" (사부; 師傅) and a "Sihak" (시학; 侍學) were appointed and received Confucian education, there were also Jo Jun (조준) and Yi Seo (이서).
The Crown Prince was said to engrossed in Buddhism and on 4 February 1391, he went to "Hoeam Temple" (회암사), where he and his parents prayed all night long.
Wang Seok then visited "Yangneung" (양릉; 陽陵) and made a sacrifice in Hyosin Hall (효신전; 孝愼殿) to announce the moved capital back to Gaegyeong.
Then, on 15th, the King delivered the Crown Prince's seal to Wang Seok through Seol Jang-su (설장수), a priest from Chanseong Temple (찬성사) and a feast was held after the ceremony.
[4] He was loved by the Ming's Emperor and he treated him to a western tea while honoured Wang as "Marquess" (후; 侯) and "Duke" (공; 公), those made the Emperor also held banquets and feasts five times for several days during the Civil War and was given away the 2 Jeong (2정, 錠) gold, 10 jeong (10정) silver, and 100 pieces of silks (견단 100필) for him.