Mitsuki Nakae’s commercial work (On my Sheep etc.) is the clearest case where 中恵光城 should be credited, but also give us a decent rule of thumb for how to apply the distinction:
- Her self-published doujin releases are almost by definition ABSOLUTE CASTAWAY releases, including Doukai Kitan, despite inconsistencies in metadata
- Her commercial releases, including those with TEAM Entertainment and SIDE CONNECTION, give credit to 中恵光城
For songs: unless a single track artist is clear in the track listing, we typically give song credits to the release artist, which sounds like it should be ABSOLUTE CASTAWAY for Mitsuki Nakae’s doujin releases. Vocalist, arranger, and lryicist credits should be entered as song relationships.
Aside: I’d give very little weight to metadata on streaming sites. They’re often entered through third party intermediaries and sometimes modified for “SEO”.