As an American man of the 1990s writing about a Japanese woman of the 1930s, I needed to cross three cultural divides - man to woman, American to Japanese, and present to past.
Geisha because when I was living in Japan, I met a fellow whose mother was a geisha, and I thought that was kind of fascinating and ended up reading about the subject just about the same time I was getting interested in writing fiction.
Memoirs give the knowledge about the author and his environment. They are different from biography. Memoirs do not get ahead, and the man who writes a biography looks at his future like at a very simple thing.
