Line is a freeware app and service for instant messaging and social networking, operated by the Korean-Japanese company LY Corporation, co-owned by SoftBank Group and Naver.

[11][19] Because Naver/NHN had a far superior cultural knowledge of what Japanese users wanted, and a much larger corporate marketing budget, Line quickly surpassed KakaoTalk in Japan.

The features allowed users to share recent personal developments to a community of contacts in real-time, similar to the status updates in social networking services such as Facebook.

Users can also share photos, videos and music, send the current or any specific: locations, voice audios, emojis, stickers and emoticons to friends.

[56] In September 2015 a new Android launcher was released on the Google Play Store, helping the company to promote its own services through the new user interface.

All proceeds earned from the sales of these stickers were to be donated to the Japanese Red Cross Society to provide financial support and aid for the victims.

[70] The service has since expanded to allow other features such as offline wire transfers when making purchases and ATM transactions like depositing and withdrawing money.

In August 2013, it was possible to intercept a Line chat session at the network level using packet capture software and to reconstruct it on a PC.

[90] Line stated in March 2021 that it had since blocked access to user data at the Chinese affiliate[88] and that it would revise its privacy policy and make it more explicit.

This included user age groups, genders, and partial service usage history, along with business partner and employee information like email addresses and names.

The leak was traced back to unauthorized access through a Naver subcontractor's computer, which shared an authentication system with Line, allowing the breach.

[100] Analysis by Citizen Lab showed that accounts registered with Chinese phone numbers download a list of banned words that cannot be sent or received through Line.

[111][112][113][114] The "Furufuru" feature on Line, which allowed users to add friends by shaking their smartphones in the same location and exchanging contact information, was found to infringe on a patent held by a Kyoto-based IT company called "Future Eye."

Line later revealed that it had reached a settlement with Future Eye and expressed its intention to continue respecting intellectual property while improving its services for customers.

The Information-Technology Promotion Agency notified Line about several critical software vulnerabilities, such as the risk of external access to chat history and photos, and the exposure of data stored on SD cards.

Most of these incidents happen through external bulletin boards, websites, or apps, where users exchange IDs and then establish contact with each other[123] 90% of girls are sexually victimized via smartphones, with the majority using Line, according to a scattering of sources.

[128] As a result, the police can only respond to requests for action,[129] while Line has taken measures such as issuing warnings about these services[130] and periodically blocking ID search features for users under the age of 18.

[131] Due to the ongoing misuse of Line for sexual crimes, Kyoto Prefecture and the Kyoto Prefectural Police have requested Line to implement measures promoting proper use, prevent the misuse of "bulletin board apps" that could lead to child pornography or child prostitution, and create systems that make it harder for users to access illegal or harmful content.

[132] In 2014, the Ministry of Education, Culture, Sports, Science and Technology (MEXT) reported an increase in bullying cases involving computers and mobile phones.

Shuichi Hirai, Director of the Division of Students and Pupils at MEXT, stated, "Bullying through platforms like Line has evolved, and it has become harder for adults to detect these incidents".

[138] On June 18, 2014, FACTA Online reported that the South Korean government had been intercepting Line's data (free calls and text messages).

[139] In response to this report, Lines president at the time, Akira Morikawa, denied the claims in a blog post, stating that there was no such incident.

[143] At that time, the details supporting both sides’ claims had not been fully disclosed, leading to comments from third parties that there was insufficient evidence to make a clear judgment.

On the morning of March 17, Chief Cabinet Secretary Katsunobu Kato stated at a press conference, "The relevant government agencies will confirm the facts and take appropriate action."

However, images, videos, Keep, albums, notes, timelines, and Line Pay transaction information are managed on servers in South Korea.

[153][154] In response to the reports, the Ministry of Internal Affairs and Communications announced on March 19 that it would temporarily suspend the use of Line services and request local governments to investigate their usage.

[157] On April 9, 2021, Akira Amari, a member of the Liberal Democratic Party of Japan, stated that Line and its parent company Z Holdings had promised to implement measures such as adopting a cybersecurity system based on the U.S. National Institute of Standards and Technology SP800-171 level and limiting data management to countries with information protection rules equivalent to Japan's.

It criticized the fact that Chinese affiliates had access to personal information stored on Korean servers, stating that economic security concerns were not adequately considered and that the system lacked a proper review framework.

In response, Line issued a statement on October 18, acknowledging that its governance and risk management systems had not kept pace with its rapid growth.

[172][173][174] From April 12, 2018, to September 20, 2020, personal information entered into the refund application form for Line Game service terminations was exposed and accessible through the Internet Archive.