A woman who appears in a book-world that corresponds to the Russo-Japan War era. She is an intelligence agent and an expert martial artist noted for sending three colleagues into hospital during training.

Yōko arrives on a train somewhere corresponding to contemporary Russian Siberia, cross-dressing as a male diplomat and attempting to link up with fellow agent Kohtaro Nanbu, codenamed "Adam", for a film containing radio codes.

(Wikipedia)