Kumamoto
From Memory Alpha, the free Star Trek reference.
Kumamoto is a city in Japan on Earth, where Keiko O'Brien's mother lived. In 2369, Keiko threatened to move back to Kumamoto after seeing the condition of the living quarters on Deep Space 9. (DS9: "Emissary")
- It is unclear in just Keiko's mother lived in Kumamoto or if her father lived there as well. If it was just her mother then this may indicate that her parents were divorced, as it was later established that both of her parents were alive later in the series.
