Young idol bands depend heavily on their fan base, which is in its way as manufactured as the bands themselves. They need supporters, consumers, and evangelists, and the fans are all of these. Too great a dependence on their fan base is one reason why many idol bands are almost unknown to the general public. But TWICE became one of the few exceptions.
TWICE's international members were the key. The very presence of Japanese and Taiwanese members was expected to draw some attention from the public, but it also proved explosive.
In November 2015, only a few weeks after their debut, the foreign members -- Sana Minatozaki, Mina Myoui, Momo Hirai from Japan and Chou Tzuyu from Taiwan -- appeared on a Korean TV show and waved their national flags to identify themselves.
As usual in the overheated atmosphere of trivial media pursuits, the online patriots in Korea and mainland China overreacted and scratched frantically at their historical enmities. To make it worse, a pro-Chinese singer, Huang An, denounced Tzuyu publicly claiming that waving Taiwanese flag on Korean TV is an act of treason against the motherland.
Chinese media reacted by barring most of TWICE's promotions in China. Crushed by public opinion, Tzuyu released a video apology online in January 2016. Park Jin-young, the head of JYP Entertainment, sent out an apology too.
But then Tzuyu's apology backfired in turn, shocking and infuriating the Taiwanese who were poised to vote for pro-independence candidate Tsai Ing-wen in the presidential election a few days later. Even Koreans, normally the first to take umbrage at any perceived slight to their nation, turned their backs on the nationalist squabbling.
In the long turn however, all publicity is good publicity, and TWICE's foreign members were now internationally known, and public opinion came round to their side.
TWICE's popularity skyrocketed. Their second single "Cheer up," released four months after the flag incident, was an immediate hit, and Sana's "shy shy shy" line with its peculiar dance move intoxicated Koreans. It topped all Korean pop charts, and the video reached 100 million views in 207 days, the fastest ever for a Korean girl band.
The next song "TT" went even further. The "TT" move -- a double T gesture with the two hands pointing down together beneath the chin -- went viral among Japanese youngsters and turned into "TT syndrome."
Videos imitating their dance moves boomed as well. There are more than 2 million video clips associated with it on YouTube, and at a dance contest in November 2016, 1,099 teams from 62 countries applied to perform.
The single also broke the record of the fastest K-pop music video to reach 100 million views in January 2017 with 71 days, and the record was broken again by TWICE's other song "Likey" with just 33 days.
Likey means the "I like it" sign on social media, and this title reflects TWICE's strategical focus on the lifestyle of the youngsters mostly based on the internet, the indispensable companion of the K-pop industry.
TWICE had released 20 singles and albums as of February 2018 and sold more than 2 million worldwide. Their seven music videos since 2015 have reached 100 million views on YouTube. The latest Japanese single "Candy pop" has been sold more than 300 thousand copies in the first week of its release and ranked at the top of the Billboard Japan Chart.
Success put the media spotlights on the three Japanese girls. Newspapers and TV channels in Korea and Japan reported competitively about how the three girls debuted in Korea and came back to Japan as K-pop stars.
"It is not just a comeback for K-pop but an evolution," one Japanese article gushed. "The K-pop industry now takes on a truly multinational nature. It makes use of the Internet as its global marketing tool, and this strategy works brilliantly. More and more Japanese youngsters are going to Korea looking for success."
The three girls' popularity in Korea and Japan is even supposed to have played a role in softening historic enmity between the two countries. "Young Koreans and Japanese think pop culture should be separate from political and historical issues. The emergence of Japanese K-pop stars shows that the future of the two countries could be very different from now. The three girls are the first of their kind. We are going to see more like them."