I really do think that Arachne is Rose's mom and the final boss. I don't see how it couldn't be, unless Arachne is a side mistress like a lot of the 6F women were, but like we've seen the previews, Arachne is being given a full floor treatment, the fact that a character like Arachne has been given so much mystique to just NOT be important is next to impossible in my mind.
Also yeah maybe she isn't as sexy or whatever as the others because she's overweight, but like we know as well as anyone that some people just like thicc MILFs, and there's not much we can do about it since this is Bo's game. The Chinese audience probably is more into it anyhow so Bo isn't going to give a fuck what we think about his characters.
Honestly dude, we really don't need another Yugata, she was fun as a fandom wank machine, but like she got a little annoying after she decided that the "anti Jessica" shtick was all she was ever going to do.
Do you really want to die on this hill? Even if Arachne is a minor character, she's going to be in the game, so why get carpal tunnel on your "glorious crusade" against a porn game character that no one actually cares about?