The sixth episode of The King: Eternal Monarch featured a war sequence between the Kingdom of Corea and Japan. The subplot unfolded to convey that the Japanese warships breached into Corea's waters and paved the way to war.
The battle also saw Lee Min-Ho dressed up in a crisp white uniform to lead the navy. While fans couldn't stop gushing over the actor's look, many viewers were enraged by the battleship in the naval war shown in the parallel universe on the episode.
Several viewers pointed out that the supposed "Japanese" warship appearing on the series, carrying the Japanese flag, share an extremely close resemblance with historically representative naval ship designs of the Korean navy.