@Goalkeeper
This will be pretty interesting.

I'm not quite sure why the author never made an attempt to wrangle in copyright, it would be kinda strange they didn't know about the uses until now. However it could have been a foreign copyright issue and not worth dealing with. But with a Japanese company involved now it probably is worth dealing with.

I wonder WTF mythic is doing, because as the largest indie vtuber the question of "does she own the rights to her model" should have been the first thing dealt with as someone arranged these merch deals. I highly doubt Filian did all these deals herself.