"I'm a huge Beumrae fan," the woman seated next to me gushed during the intermission, pointing to a glossy photo in my program. "His voice gives me chills."

Makiko, as I'll call her, was seeing this production of "Jack the Ripper" for the fourth time. And though she claimed she wasn't a "superfan" of Korean music and drama, she could trot out detailed pedigrees of every actor in the program — especially Kim Beumrae, the incredibly deep-voiced star in the title role.

Makiko's companion, Junko, was very much a superfan who personified why the "Korean wave" is such big business in Japan and across much of Asia. She's been to South Korea multiple times to shop and see concerts by K-pop supergroups. And she, like millions across the region, also swoons over Korean TV series and adores music by bands such as Super Junior and F.T. Island.