It’s clearly a “Japanese drama”. (Because the location, background, and many of the actors are Japanese)
but
Labeled as “”Korean drama”” by investment and distribution company Netflix
(Because it is directed by a Korean director, stars a Korean actress, Han Hyo-joo, and features several Korean actors)
Will Everything Come True? Netflix Weekly Global Results
It is popular in Eastern Europe as well as the Middle East and South America.
Because it is difficult to distinguish between Korean and Japanese faces,
(Just as we cannot distinguish between Western faces, Americans, British, and Germans)
It became popular thanks to Netflix labeling it as a “Korean drama.”