Shingo Katori commanded the adoration of millions of fans across Asia as a member of SMAP, one of Japan's most successful boy bands. After decades as a ubiquitous TV presence, he finally decided in November it was time to get an Instagram account.

A small step for one celebrity highlights a sea change for the advertising industry in Japan, which has lagged much of the developed world in switching from old to new media. Katori, now a solo performer, has promoted everything from beer to cars on TV — now he also has more than a million followers on Instagram alone.

"I was raised on TV for 30 years," Katori, 41, said in an interview in Tokyo. "But now I spend half my time on social media and watching streaming services."