Keiko Yamasuki is Bill Hines’s wife, and she works alongside him in his research. She is a former Nobel Prize winner, and she won the prize for applying Hines’s neuroscientific research to treatments for amnesia and mental illness. Keiko is also eventually revealed to be Hines’s Wallbreaker, meaning she is a member of the Earth-Trisolaris Organization (ETO), a pro-Trisolaran group of humans, who aims to uncover Hines’s true plan as a Wallfacer and expose it to both the Trisolarans and the rest of the world. She ultimately succeeds in that mission, which causes Hines to be shunned by society.