How should artists be credited on a work released within an "interactive music project"?

Hi, I’ve run into a very strange set of releases that I don’t know how to properly enter into Musicbrainz.

Here’s the WEB release: MILGRAM コトコ (CV: 愛美) | Spotify

I’ve added both versions, but I am unsure if I have entered the artist credits properly
CD: Release “HARROW” by MILGRAM コトコ (CV: 愛美) - MusicBrainz
WEB: Release “HARROW” by MILGRAM コトコ (CV: 愛美) - MusicBrainz

There are additional releases under the MILGRAM project that I am not planning to add now, but how I credit this particular release will determine how the other releases should also be entered: DISCOGRAPHY - MILGRAM - UNIVERSAL MUSIC JAPAN

Here’s the background as I understand it:

MILGRAM is an “Interactive Music Project” by DECO*27 and Takuya Yamanaka. There are music releases released under the umbrella of this project, as well as additional content such as videos, websites, lore, ARG elements, etc. See: MILGRAM Wiki | Fandom

I am unclear on what type of musical input the project itself has on the releases released under it.

I am trying to add the Single release “HARROW”. The artist credit for this release on the CD store as well as Spotify is “MILGRAM コトコ (CV: 愛美)”. Breaking down the parts of this artist credit:

MILGRAM: The Interactive Music Project
コトコ: The name of the fictional character that exists within the MILGRAM lore
(CV: 愛美): 愛美 is the real person who performs the vocals of the コトコ character

The final track of the release is a collaboration between “MILGRAM コトコ (CV: 愛美)” and “MILGRAM エス (CV: 天海由梨奈)”. Each of those credits have a fictional character and a real person who voices that character.

So for entering this credit into Musicbrainz, I can think of four possible formats.

  1. The entire artist credit “MILGRAM コトコ (CV: 愛美)” is used for “artist as credited”. The artist link is to the character vocalist. This is what I’ve originally gone with.
  2. A new artist named “MILGRAM コトコ (CV: 愛美)” is created. This is credited as-is.
  3. The artist credit is broken into it’s three pieces. MILGRAM, which is a Other type artist, コトコ, which is a Character type artist, and 愛美, which is a Person type artist. The Final Track will be credited as “MILGRAM コトコ (CV: 愛美) & MILGRAM エス (CV: 天海由梨奈)”. That’s a total of 6 artist credits, and MILGRAM is credited twice for the same track.
  4. The artists credits are split into three pieces, but the project’s name is only included for the first one. The final track will be credited as “MILGRAM コトコ (CV: 愛美) & エス (CV: 天海由梨奈)”. That’s a total of 5 artist credits.

I’m leaning towards either #3 or #1, but I’m unsure. Any input on this would be appreciated. Thanks!