Chapter 7:
Kurama, the de-facto ruler of Looking Glass City, tells Koto that their mother is the black rabbit.
Chapter 8:
Kurama has been intellectually curious from a young age, and loved it when his father praised his inventions.  He wants to find what he can do outside of the Looking Glass City.
Chapter 9:
The identities of Doctor Shouko and Fushimi are revealed...
The words "black rabbit" do ring a bell...
Klingelt etwas, wenn ich die
 Wörter "Schwarzer Hase" sage?
Las palabras "conejo negro" 
me llamaron la atención...
Me llaman la atención las 
palabras "conejo negro".
Je connais un lapin noir,
si c’est ce qui t’intéresse…
As palavras "coelho preto" são familiares...