By the way, how do you guys process the other playable characters in a mainline game?

For me, I like to think that they all go together. But the boss fights are solo. Think how Memories of Phantasm delegates EoSD – Reimu encounters Rumia and Meiling, while Marisa encounters Cirno and Patchouli.

So in this case, it might be Marisa who's dueling Nazrin, while in the meantime Reimu and Sanae deal with all the other fairies and mobs that come out of the woodwork to play danmaku.