You're really, really, really almost convincing me hope for spontaneous awkward resurrection, or alternatively, Midori-and-Kikuko-ghost-buddies after a near-death-actual-death experience later in the story. Or- hell! Who says we can't live our life? We'll just be- we'll just be corporeally challenged! We'll get some false documentation, put regular clothes over our meguca outfit, get a shady takeout delivery food job! Rob the Yakuza on the other side of Japan for all their cash monies and then liquidate it somewhere on the mainland or something- we'll get really good at money laundering! Put ourself through sketchy internet college/a community college in America if Midori decides to go to an American school so we can road-trip along! Work remotely over the internet in CS or as a reporter or an advice columnist! Or keep up the shady delivery job! Pay rent or haunt luxurious upper levels of hotels!
Maybe they won't be the same exams, maybe we'll have to pay off a shady government official willing to let us get away with a fake identity- but we'll take those damn exams! We'll get a job, go to college- if we have to, we'll sneak into college and spookily write all our attempts at answers on the blackboards while nobody is looking! Walk around a campus as a slightly-odd student who definitely goes to class but nobody knows where they live! Borrow textbooks and access to the course websites from friends, complain about how the university computer system sucks for not recognizing how we're totally a registered student, we swear! Go to our own damn graduation, our own damn reunions- Hell, there's magic around, learn some illusions so it looks like we're growing up, to the rest of the world! Or get really good with disguises and makeup, I guess.
And maybe we won't grow up, but we'll grow older. We'll be Midori's friend for as long as she wants us to be (assuming this conversation and teamwork goes well, anyway), and if we grow close enough we want to have been able to spend a life together, we'll spend the rest of her life together, mortality be damned.
And hey. Death seemed like a pretty chill person. In the end- and all things do- who's to say we can't finally take the last ferry out of life together, someday far from now?
[X] Tell the truth. (Explain that you're Yukimura Kikuko, and you're a ghost.)
-[X] Thank her for caring that you were gone. (A lot of people were perfunctory at the funeral)
--[X] "...Err... I may slightly be Kikuko's ghost? I mean I am Kikuko but I'm also a ghost, but I'm only a ghost because they were running out of magical girls so they started asking dead people?"
---[X] Frantically apologise for making things so awkward and possibly traumatising her or whatever we've done.
That's all assuming we don't both bad-end or awkward-end in the meanwhile, of course. But there's nothing wrong with a little Hope.
Magical girls are all about the making with the miracles and dreams, yeah?