If you were charged after you canceled, here are some possible reasons.
 

• You haven’t completed the cancellation process
  Go to account settings (https://account.nicovideo.jp/my/account) to check your current membership status.


• You might have an additional premium account
  We charge membership/subscription fees per account. You might be using different emails, phone numbers, or social media accounts such as X（Twitter）/Facebook to sign up for the premium membership. Please try logging in with all the information that you can recall checking your current membership status in your account settings (https://account.nicovideo.jp/my/account)