Line Corp., operator of Japan's most popular mobile messaging service, filed confidentially for an initial offering in the United States, people with knowledge of the matter said, taking a step closer to a dual-listing in New York and Tokyo.

Morgan Stanley is managing the U.S. share sale, said the people, who asked not to be named because the process is private. Companies with less than $1 billion in revenue can submit their filings privately under the Jumpstart Our Business Startups Act, which is aimed at encouraging smaller companies to go public.

Line, a free messaging service that makes money by asking smartphone users to pay for teddy bear icons and games, has more than 470 million users in 230 countries, according to its website. The company, controlled by South Korea's Naver Corp., also submitted an application for an IPO to the Tokyo Stock Exchange, according to a statement Wednesday. The offering could value the company at more than ¥1 trillion ($9.9 billion), people familiar with the situation said this week.