Artist roles
Animator
Japanese: Most commonly credited under 動画.Person who made or animated the PV. Required for Music PV and Drama PV song types.
Arranger
Japanese: 編曲Arranger is the person handling the instruments and producing the music. Most of the time this is related to remixes where the remixer is generally credited with the arranger role, but sometimes for original songs the roles for composition and arrangement (music production) are divided as well.
Composer
Japanese: 作曲The person who created the song. Most of the time for original songs, the composer and arranger are the same person, but not always.
Distributor
Mostly for albums, the person or group who distributes the album, either physically (such as selling at an event), or electronically (sells the digital copies).Circles get this role by default. Sometimes it's necessary to give the role to custom artists, other groups or individual artists if they're handling the distribution.
Illustrator
Japanese: Most commonly credited under イラスト or 絵.Person who made the illustration for either a PV or album cover. Also booklet illustrations.
Instrumentalist
A person playing an instrument, usually a physical instrument such as piano or guitar.Lyricist
Japanese: 作詞Person who wrote the lyrics.
Mixer
Person who did the mixing.Other
For all roles that don't fit with any of the predetermined options.Publisher
Usually a label or a circle, the group or sometimes a person who published the album.Vocalist
A person or synthesizer producing vocals.Voice manipulator
Japanese: 調声Person who operated the voice synthesizer.