Hé Kingyami,
I (think I) understand whay you're trying to do, guess (!) it's impossible though (for now).
If I'm wrong, others will correct me.
Yet I think about these workarounds:
How about creating 2 custom tags: 'soundtrack' (for instance) and 'series' (fi).
Soundtrack, you use for anime or game.
Then, in music explorer, you can choose soundtrack in the thumbnail browser.
And in your main panel, you can right click on 'Artist information' and set 'soundtrack' as filter (of course, when 'show filter panel' is checked).
Both 'anime' and 'game' will show up in the filter panel and you can easily navigate them.
Also, in your tabs, you can 'set displayed fields' and make 'soundtrack' (and/or 'series') visible.
Depending on your sorting settings or manually, you can then also easily navigate them.
A few ideas, maybe (?) helpful.
Maybe you know all this - in that case, forgive me for 'mansplaining' you ;-)
Greetz, b.
PS: I understand changing your tags could be kind of disencouraging. Yet you can do that in the blink of an eye with the tagging tools of MB and/or the plugin from Boroda (with extra tagging tools).)