Mobile messaging giant Line on Thursday launched a digital music streaming service in Japan, stepping into a largely untapped market still dominated by sales of compact discs.

The new business -- which comes weeks before Apple is expected to enter the Japanese market with its own streaming service -- offers unlimited access to a collection of more than 1.5 million songs for 1,000 yen (US$8) a month.

For those on a budget, a 500-yen fee buys 20 hours of listening time.

Line said it would expand its music library to five million tunes by the end of the year, and to 30 million in 2016.

The service will feature top-selling artists, from Sam Smith to Michael Jackson, as well as likes of Japanese diva Ayumi Hamasaki and Korean band Big Bang.

Line Music said it plans to set up accounts for artists where they can send messages and offer glimpse of their lives to their fans.

Japan is the world's second largest music market, estimated to be worth $2.6 billion in 2014, after the $4.8 billion US market, according to the Recording Industry Association of Japan.

But packaged media such as CDs account for about 78 percent of Japanese music sales, contrasting sharply with the US market  markets where digital downloads are soaring.

Many Japanese production companies have focused on established retail channels for CDs while issues over licensing have also hampered growth in the streaming business.

Apple says its new Apple Music will launch on June 30 in 100 countries, offering up a heavyweight rival to online services such as Spotify, Pandora and Jay Z's fledgling Tidal.

Line's popular messaging app, which is hugely popular in Japan and other parts of Asia, lets users make free calls, send instant messages and post photos or short videos. It combines attributes from Facebook, Skype and WhatsApp.

Best known for letting users send each other cute cartoon "stickers", Line is hugely popular in Japan, particularly among teenagers. It is reportedly planning an initial public offering later this year.

The company's music venture is also jointly held by Avex Digital and Sony Music Entertainment. Universal Music also plans to join the venture, Line Music said.