Everyone knows Doki is Selen. That is public knowledge. It makes as much sense as Altare and Axel and their PLs being back with Doki and all "TSB is back!"Sachi is a very long time friend of Doki.
When Doki asked her, she obviously would do it as Sachi. Was there even any interaction between Mumei and Doki? Doki randomly having Mumei in her video would make no sense.
Maybe. I just think that would be odd, even if you factor in the whole "ID and Stars can play looser with the rules" thing. It all isn't really a big deal, either way, it just struck me as odd.Different rules for Holostars perhaps?
Could even be that she just hasn't asked management for permissions, so only Stars management have givent the okay for them. Them being able to collab with her is recent, too. Hell, we don't even really know if they gave a "no" to collabs with her to begin with. That was just the assumption.