what's the function of Yoshiko in the book? What function does she serve in relation to gunnar's identity?

I think like much of the book, the character of Yoshiko the mail order bride is satirical. Like Gunnar, she is a visible minority but different. She affects Gunnar's identity both as a black man and a man in general. In many ways she is an existential extension of Gunnar's obsession with racial identity.