Baccano 1705: The Ironic Light Orchestra was one of the better books in the series; a tightly focused book with an unusually small cast for Narita: three characters, two we already knew, and one who clearly did not end up becoming immortal. Indeed, later books reveal that she died in 1710, so this book was always going to be the story of how she met her end.
Narita admits in the afterword that he found it incredibly difficult to kill her off, and declares that he will never do this again. It really sounds like he wrote himself into a corner he couldn't get out of. He doesn't seem to have had any actual story to go with what we already knew, so this book ends up like an insanely boring Cliff's Note retelling of something like two years of disconnected scenes that never add up to anything. It felt like the plot didn't actually gel till page 282, and it ended another twenty pages later. The embarrassing framing device involving this narrative retold by a poet drives home just how tedious and leaden the whole affair is, and the M. Night Shyamalan worthy series of bad idea shocking twists towards the end makes this the single worst thing Narita has ever written. Hopefully he knows it and will avoid ever forcing himself to write a book he has no interest in actually writing.