Thank you for using Niconico.
The application for Twitter-account linked logins will be changed on Tuesday, January 20th.
For Twitter-account linked users, you will need to verify your information with the new application when you use your Twitter account to initially login to Niconico from the 20th (Tuesday).
New Application Name: Niconico Login link
We appreciate your understanding and apologize for the inconvenience.
Thank you very much.