Nana has parallel meanings. In Japanese (七), it means "seven" — the number of completeness. In Greek and many languages, Nana is the affectionate term for grandmother. In Akan, Nana is a royal title for both kings and queens.
Nana is the iconic dog-nanny in J.M. Barrie's Peter Pan; the manga and anime Nana by Ai Yazawa is a cultural phenomenon.
Nana reduces to one — the number of Japanese seven.