huh... I remember something like this from the novel, and I remember it being really boring, this was probably like 4-5 years ago? so I thought it was the WN.
@MachineGunViperWheels
It's a common thing, when a character gets promoted in some way, shape or form, it gets axed from the main story, meaning it no longer follows the MC or the main plot. Unless some miracle happens, she's bound to be axed from the story and only appear every now and then, in other words, she got demoted from main character support to side character. It's a very common trope, I'm surprised you didn't get it...
Weird because? Why on earth would Raphtalia stay behind to defend a world that's not even hers? Rather than returning home to defend her own world and remain by Naofumi's side. And Naofumi can't even function properly when Raphtalia isn't with him.
"I got transported into an isekai, got turned into a loli and stole a hero position, but I just want to be with my master!"-the-manga coming near you this fall
@Zextrace
Never said anything about her staying in wherever they are, if she gets axed she'd probably go back to fight for her people in other places or stomp slavers, etc. And Naofumi grew a lot, he can take care of stuff by himself now, also, a new support character can be created, it's not like the cast is fixed.
It's fixed in the sense that no one will ever get as close to Naofumi as Raphtalia has. New support characters can be created, but Raphtalia remains crucial to Naofumi's mental state. What Raphtalia becoming a vassal wielder does is put them on a more even footing especially now that the slave crest is gone for good.