All joking aside, this is the volume where the story finally starts to form a concrete direction to go in. After quickly finishing up Suzumi's backstory, the story quickly shifts to the introduction of one of the final main characters: Chidori, who happened to glimpse Ceres' flying abilities in an earlier volume. She demands that the celestial maiden help her crippled brother achieve his dream of flying, although apparently Ceres would much rather run around and mess around with Aya's love life instead.
In her defense, both boys need and deserve the serious talking to that she gives them.
Speaking of which, since Aya and Toya can't physically be together nearly as much as before, it gives both of them needed time to reflect on everything that's happened between them and everyone else. Indeed, Aya actually acknowledges that her behavior around him since book one was kind of immature and shallow! Yuhi stays as jealous as ever, but in his defense, he's a stupid hormonal teenager with just as much stress on his shoulders over the Mikage situation as Aya and far less screen time to deal with it. Besides, any time that could have been devoted to him is instead given to Chidori, who is a breath of fresh air. While I don't like her personality very much, she does add a sense of brevity that's been sorely missed for the last couple volumes.
Ceres' character is actually written quite inconsistently in this volume. She emerges and disappears seemingly at random, and when shit hits the fan, she clearly knows about it... but instead seems to be content to let a series of emerging c-genomes devolve into unavoidable chaos while she chats with Toya and flies around with a child (who, I might add, is extremely vulnerable due to his inability to walk). Her incompetence clearly only serves to force Chidori to take the stage and stand for herself, but surely there was some better way to incorporate both this and her growing fondness for Aya and humans without sacrificing her intelligence.
Aki's exploration into his past life is brief, but it may be disturbing for some readers. Because after four volumes of death and destruction, clearly incest is what we needed to throw into the plot. I only note this because it only gets worse as the series progresses, and squeamish readers may want to take note before continuing forward.
In the end, this was a standard volume of the story thus far. Still good by shojo standards, but it's hardly anything to fangirl over.