What Is LINE? The Messaging App Born After Japan's 2011 Earthquake

LINE is a smartphone messaging app in wide use in Japan. If the question is when it started, the answer is 23 June 2011. According to its operator, LY Corporation, it was created as a communication service for staying connected with the people who matter, after many people were unable to reach family and friends in the Great East Japan Earthquake. In January 2026 LY said LINE's domestic monthly users had passed 100 million as of the end of December 2025.

An app born after the earthquake

LY Corporation's announcement of 29 January 2026 traces LINE back to the Great East Japan Earthquake of 2011, when many people could not reach their families and friends. LINE was born from that as a communication service for staying connected with the people who matter, and, the company says, aimed from the start to become a "life platform" that makes daily life more convenient by connecting people not only with each other but with companies, local governments and information. According to LY's special site, it was developed under the name Midori Talk, with a purple icon.

Stickers

The first LINE lacked what would become its signature feature. An official LINE blog post of 23 June 2016 says that the LINE born on that date five years earlier was an early version without even a sticker feature. An official blog post of 13 April 2012 introduces the creator of LINE's stickers as Kan, a designer employed by NHN, which then ran LINE. According to LY's special site, the early stickers centred on a character called Moon; adults were lukewarm in pre-release research, but high-school girls loved them, and that response fed the spread of stickers.

LINE Creators Market, which lets individuals and companies sell stickers they make themselves, opened in May 2014. According to LY's announcement of 28 November 2024, by September 2024 it had more than 7.5 million creators and had sold more than 23 million creator sticker packages in total.

The 2021 contractor problem

In March 2021 it became an issue that LINE users' information had been accessible from outside Japan. According to the Ministry of Internal Affairs and Communications (MIC), on 19 March it ordered LINE Corporation to report, after news reports that users' personal information on servers in Japan could be accessed from abroad. According to ITmedia, content users had posted with "public" settings and content that had been reported by users were viewable by LINE China, a sub-contractor of LINE's subsidiary LINE Plus.

On 23 April the Personal Information Protection Commission gave LINE guidance, finding that it had not taken adequate security measures in supervising LINE China. On 26 April MIC issued administrative guidance, finding shortcomings in the management of LINE's telecommunications systems and in its explanations to users. According to ITmedia, MIC said it had not found any breach of the secrecy of communications or leak of personal information resulting from the outsourcing abroad.

LY Corporation

LINE Corporation and Yahoo Japan sat together in a group under the holding company Z Holdings. According to a SoftBank announcement of 28 April 2023, Z Holdings was to merge with its wholly owned subsidiaries LINE and Yahoo Japan and change its name on 1 October to LINE Yahoo Corporation (LY Corporation in English). According to LY's timely disclosure of 2 October 2023, the reorganisation, in which Z Holdings absorbed Yahoo Japan and others and took over LINE Corporation's business by a company split, was completed as planned on 1 October, and the company changed its name to LY Corporation.

The 2023 leak and the ministry's guidance

On 27 November 2023, shortly after the new company was formed, LY disclosed a data leak caused by unauthorised access. According to the announcement, a PC belonging to an employee of a contractor used both by NAVER Cloud, a related company in South Korea, and by LY was infected with malware. Because a shared authentication system that managed employee information gave access to the former LINE Corporation's systems, a third party gained unauthorised access through NAVER Cloud's systems on 9 October.

The announcement says bank account details, credit card data and the content of chats in the LINE app were not included.

On 5 March 2024 MIC issued written administrative guidance to LY. The guidance document held that the leak of users' communications information was a breach of the secrecy of communications under the Telecommunications Business Act, with at least 20,000 items (including estimates) leaked. As causes it cited heavy dependence on NAVER's side for systems and networks dating back to when NHN Japan, the predecessor of the former LINE Corporation, was a NAVER subsidiary; technical shortcomings such as not requiring multi-factor authentication; and inadequate supervision of contractors. It added that a relationship in which LY was under considerable capital control by its contractor, with the NAVER group holding half the shares of LY's parent A Holdings, had made it hard to demand proper measures from the contractor, and asked LY to press its parent companies to review its management structure, including that relationship. The document also noted that this had happened despite guidance on 26 April 2021 that had already called for stricter access management.

According to Impress Watch, MIC issued a second round of guidance on 16 April. Because LY's 1 April report, among other things, put complete network separation from NAVER's side more than two years away, MIC said security and contractor management could hardly be called adequate yet, and asked LY to report concretely by 1 July on bringing the separation forward and on the outlook for reviewing the capital relationship.

According to a Kyodo News report, by the end of March 2026 LY had finished separating the systems it had shared with NAVER's side, including at subsidiaries, and had ended its development outsourcing arrangement. The internal affairs minister, Yoshimasa Hayashi, told a press conference on 17 April that the response was progressing steadily. The same report said NAVER remains LY's de facto largest shareholder.

On 28 March 2025 MIC issued another round of administrative guidance to LY, finding that a problem in which thumbnails in LINE's album feature showed parts of other users' images amounted to a leak of communications protected as secret.

Lineage

LINE belongs to the same current as WhatsApp, which used the phone number to keep people in touch through an app. Among Japanese social networks, invitation-only mixi came before it. Japan's habit of using the internet on mobile phones goes back to i-mode. For the wider story, see the social media timeline and the mobile timeline.