AniDB is a user-edited database on anime. There are several entities for which it seems to make sense to have links:

An AniDB "Creator" corresponds to a MusicBrainz Artist:
https://anidb.net/creator/176
https://musicbrainz.org/artist/b59a59e9-b997-4a38-855d-19f00ed42e52

An AniDB "Character" corresponds to a MusicBrainz Artist of type Character:
https://anidb.net/character/8968
https://musicbrainz.org/artist/a9c888d0-51a1-479f-bc7f-509f0fa1cab6

An AniDB "Collection" corresponds to a MusicBrainz Release:
https://anidb.net/collection/4451
https://musicbrainz.org/release/e5b531c3-cee1-4bbd-98d7-c5345017a3c4

An AniDB "Song" seems to correspond to a MusicBrainz Recording(s), but it also stores writer credits that would go on a MusicBrainz Work:
https://anidb.net/song/18557
https://musicbrainz.org/recording/626b094e-4d39-4edf-a80f-38e04d781397
https://musicbrainz.org/work/3b698bb2-7b84-3f30-a2a0-62d126c09bd0