@FStubbs
I don't think "yandere" is the correct term here.
Hayashi is obsessed with Kamishiro, enough to be rebuilt as a short-lived freak if it helps feed said obsession. It's not romantic as she has no empathy to begin with, but there have been multiple instances where she expressed sadism, and as she said herself, being hated by Kamishiro brings her "joy" or whatever she thinks joy is.
Still, she's always been CID's most dangerous member and now she has Neibu's OTK gift, and possibly whatever other heightened attributes come with ID. I see final boss material here.