It refers to the list of tags and collaboration list on Nijisanji Wiki. (Updates and additions to tags may be delayed as updates to this page are irregular.)
I think there are many that are not actually used as tags, but it is up to you to decide whether or not to use them for tweets.
When using tags for tweets, please be sure to check the precautions for tag usage from each Liver.
You can search with multiple words if you put a space between them.
A tag is added to the “selected tag” with the “” button, and you can tweet with the “Tweet with selected tags” button. You can cancel the selection with the “✕” button of the selected tag.
Tags not in the list can be added temporarily here.