On the 21st, at 9:40 PM, MBC aired the fifth episode of 'Moon River' (directed by Lee Dong-hyun, written by Jo Seung-hee), featuring an unprecedented body swap between Lee Kang (played by Kang Tae-oh) and Park Dal-i (played by Kim Se-jeong).
In this episode, Park Dal-i, after realizing the body swap following a near-drowning incident, frantically roamed the palace, shocked to discover her body had switched with Crown Prince Lee Kang. Lee Kang, equally stunned, confided in Lee Woon (played by Lee Shin-young), who remained skeptical.
Lee Kang, attempting to sneak into the palace by hiding in a cart, was caught and brought before the Grand Queen Dowager Han (played by Nam Gi-ae). With a face identical to the Crown Princess, Lee Kang astounded the Grand Queen Dowager by accurately guessing her intentions. Eventually, Lee Kang struck a deal with the Grand Queen Dowager to infiltrate the palace as a eunuch. She commanded Lee Kang to "steal the Crown Prince's heart and conceive an heir, and I will spare your life," threatening him with "Do you think I only kill according to the law?"
As Park Dal-i, now the Crown Prince, began adapting to the new body, receiving acupuncture treatment from the royal physician, she demanded to see her original body, Park Dal-i. Lee Kang, now a eunuch, appeared before Park Dal-i, revealing the red scar on the wrist as the spot that glowed before the swap. Lee Kang told Park Dal-i, "We need to lift your house arrest."
Reunited, Lee Kang and Park Dal-i sought ways to reverse the body swap. Lee Kang suggested, "Why not try what we did that day again?" leading to an attempted kiss. However, the swap remained unchanged. Park Dal-i then pushed Lee Kang into the water, attempting an underwater kiss, but Lee Kang struggled for breath, thwarting the plan. They tried kissing again at the river where the swap occurred, but to no avail.
Ultimately, Lee Kang advised Park Dal-i, "You must truly become Crown Prince Lee Kang," emphasizing the need for proper speech and attire, and detailing palace etiquette. As Park Dal-i's adaptation to the Crown Prince role began, she was seen cheerfully greeting the king and playing Go, while Lee Kang adjusted to life as a eunuch, lamenting, "I should have just become a court lady." The sight of Park Dal-i, in the Crown Prince's form, caring for Lee Kang astonished the ministers and officials, sparking rumors of a transformed Crown Prince and a eunuch resembling the Crown Princess bathing together.
During a nighttime stroll, Lee Kang and Park Dal-i shared heartfelt conversations. Park Dal-i revealed her past as an orphan taken in by non-biological parents. Lee Kang comforted her, saying, "It must have been very cold." When Park Dal-i mentioned setting her own birthday as 'winter night,' Lee Kang reassured her, "Your fate isn't dirty; you're very lucky." When asked about her dreams, Park Dal-i expressed a desire for a life "wearing flower shoes instead of straw shoes," settling down, and creating a family. Touched by her dreams, Lee Kang took her under a tree showered with flower petals, saying, "Let's make your season a spring night, and the path you walk a flower path." He added, "Don't drift away," spending the night with Park Dal-i. The next morning, everyone in the palace witnessed them lying together, foreshadowing challenging palace life ahead.