Spoilers!! (kinda)
Story-wise these dramas aren't that similar, but Endless Sea reminds of Twelve Letters. The idea of two young people trying to change their parents' / grandparents' fate with a letter as the key seems similar. While Endless Sea is about a time loop where both leads end up on the same day several times, trying to break the loop; Twelve Letters features the characters from the present trying to connect to the leads from the past via a letterbox.
Twelve Letters is much more complex and heart-wrenching, and Endless Sea is a quick, easy watch.
Story-wise these dramas aren't that similar, but Endless Sea reminds of Twelve Letters. The idea of two young people trying to change their parents' / grandparents' fate with a letter as the key seems similar. While Endless Sea is about a time loop where both leads end up on the same day several times, trying to break the loop; Twelve Letters features the characters from the present trying to connect to the leads from the past via a letterbox.
Twelve Letters is much more complex and heart-wrenching, and Endless Sea is a quick, easy watch.



