Everything changed for Yuta Tsuruoka when his mother, who runs a small shop in rural Japan, made a passing comment: She wanted to set up her own online store but didn’t know how.

"That was the start of it all,” Tsuruoka, 30, said. "We were in a world where people with no internet skills and no money, like my mom, couldn’t imagine creating online businesses.”

Tsuruoka, who was an intern at a crowdfunding startup, decided to develop software to help individuals and small businesses create internet shops. He founded his own company, Base Inc., in 2012. Its shares are up more than sixfold since listing last year, even though they’ve fallen sharply from an October high. That’s pushed its market value to about $1.7 billion (about ¥176.7 billion) and made Tsuruoka rich.