I don't mind early confessions and fast romances, I'll take what I can get in a series where life is particularly fragile. It'd be amazing if Shinpei can return the confession, but we'll see.
I want to believe this is somehow the real Ushio and not a shadow. Even if she turns out to be alive after all, it still doesn't change the main conflict which is to keep Mio (and themselves) alive against this supernatural shadow menace. They'll probably have to keep her existence a secret for a while though, because she's already dead on paper after that funeral.