Nico Nico Douga

Niconico (formerly Nico Nico Douga, abbreviated as NND) is Japan's largest video-sharing service provided by Dwango. "Niconico" is a Japanese ideophone meaning "smile." Before Niconico's creation, concerns were raised about copyright and the legality of the service. The staff at the time decided that instead of opting for a cool, flashy name, it would be better to go for a friendly name, as this could potentially help them gain public support and avoid problems later on.

Users could upload and view video content. However, Niconico was unique at the time in that user comments were overlaid directly onto the video, synchronized to a specific playback time. This allowed users to comment and view comments directly related to an event in the video, helping to create a shared viewing experience among users.
Bilibili, a Chinese video-sharing service, now uses the same commenting model.

When Nico Nico Douga first launched in January 2007, it originally used YouTube as its video source, but allowed users to post and view comments from other Nico Nico Douga users. These comments were overlaid directly onto the video and scrolled across the screen from right to left. Nico Nico Douga's increased access put a strain on YouTube's infrastructure, leading them to block Nico Nico Douga's access in February 2007, rendering the service unusable. However, several weeks later, in March 2007, Nico Nico Douga was relaunched, hosting videos on its own servers.

Due to a growing user base overseas, Niconico is now available in Taiwanese, German, Spanish, and English. As the company has grown, several spin-off services have also been developed that go beyond video-sharing services. These include Niconico Live Streams, Niconico Images, and Niconico 3D, among others. Celebrities often use the live streaming service for promotional broadcasts. While the name "Nico Nico Douga" was originally used as a blanket term for all of these services, the new standardized name "Niconico" was implemented to reflect the fact that Niconico was now more than just a video-sharing service.

Nico Nico Chokaigi

Nico Nico Chokaigi (literally Nico Nico Super Meeting) is an event organized by Dwango. The concept is to become a real-life recreation of the Niconico world. Singers, dancers, gamers, cosplayers, Nico Nico personalities, creators, and users all come together in a massive offline meeting to physically interact with their peers. Excerpt from the event's English PowerPoint presentation:

“This event serves as a platform for Japanese subculture; you'll find people from all walks of life—from politics to entertainment to science and technology—coming together to laugh, sing, dance, and just have fun! [...] We believe the connection between our users (people), our content (objects), and our plans (things) is special. Chokaigi brings together a dichotomy of genres from digital to analog, from content to producer, from traditional to technological under one roof.”

Although the service has seen its audience decline over the years, Nico Nico Chokaigi remains a consistently popular event with record numbers of attendees each year.

Each year, Chokaigi is announced with a different slogan surrounding its goal of bringing fans and creators together. The slogans so far are as follows:

Year: Slogan
2012: “Together we are stronger”
2013: “You will create it”
2014: “Everyone is a protagonist”
2015: “This country is full of Gee-Oh-Dees”
2016: “This site is a miracle created by all of you”
2017: “Amidst the landscape, you will find a whole new ‘now’ here”
2018: “What is ordinary for you is “special” for someone else”
2019: “Being equal is joyful, being different is fun”
Being an event dedicated to the culture of Nico Nico Douga, Vocaloid producers also have a stage for themselves, each edition of the event has presented Hatsune Miku and other Vocaloids, through animated 2D streams or 3D holographic projections in recent years.

Official website
Wikipedia