Tune in Next Time...
In a way, the whole last third of the book is an ending—it marks the end of Karou's journey of self-discovery. Because she discovers that her "self" is an entirely different person, Madrigal. And that mean's she's not actually "of this world"; she's not human but a reincarnated chimaera, from an entirely different universe.
Wow. That was a pretty satisfying ending, huh?
But then there's the actual final page of the novel, which is in the brief Epilogue. After finding out that Akiva killed Brimstone (gasp), Karou decides to leave him. She flies away with Razgut (double gasp) through the portal in the sky, to the Elsewhere.
In the previous chapter, Karou realizes that "peace wasn't the only way to end a war" (60.44). What other ways are there? Ice cream socials? More war? What exactly is Karou up to in the Elsewhere?
And, most importantly: is she going to stay mad at Akiva forever? We'll have to read the sequel in order to find out.