A Japanese government panel is investigating the parent company and operator of the Line messaging app over its management of people's personal data.
The Personal Information Protection Commission launched the investigation into Line and Z Holdings on Wednesday.
Fukuura Yusuke, Personal Information Protection Commission Secretary General, said "The panel will take the necessary steps if it finds that improper actions have been taken."
Line is Japan's most popular messaging app. It has about 86 million users in the country.
It was revealed earlier this month that engineers at the Chinese firm managing Line systems were able to access personal information.
That information included names and telephone numbers stored in Japan's server.