Both Heaven's Soldiers and Immortal Admiral Yi Sun Shin are set in the Japanese invasions of Korea of 1592–1598 or Imjin War and about Admiral Yi Sun-sin.
Both Heaven's Soldiers and The Admiral: Roaring Currents are set in the Japanese invasions of Korea of 1592–1598 or Imjin War and about Admiral Yi Sun-sin.
Both are time slip comedies in which MCs go back in time and meet Admiral Yi Sun-sin (Heaven's Soldiers) and FL goes back in time and meets the great King Sejong (Splash Splash LOVE).