NEW YORK, NEW YORK - FEBRUARY 21: (L-R) Jimin, Jungkook, RM, J-Hope, V, Jin, and SUGA of the K-pop boy band BTS visit the "Today" Show at Rockefeller Plaza on February 21, 2020 in New York City.

BTS were already massive in their native South Korea in 2017 when they scored one of their defining hits, the emotional ballad “Spring Day.” It was a poignant tale of grief and loss. Three years later ...