Like a lot of Americans I get my history from pop culture (I know, I know)... I recall reading in “Shogun”, by Briish author James Clavell, that Nagasaki was a major center of Catholic dating from the late-1500’s. It should be noted that Nagasaki was the secondary target, however. I believe Kokura was the primary, but it was obscured by clouds. I don’t know what the religion break-down is for Kokura, so it might not make any difference.
I will need to research further the relationship of these recently canonized to the original twenty-six Martyrs of Japan
http://en.wikipedia.org/wiki/Twenty-six_Martyrs_of_Japan
for those interested in the history/story of the early Catholics in Japan..I recommend looking into the book "Silence" by a famous Catholic author Shusaku Endo...
be forewarned, it tries one's heart and will make you think deeply about the meaning of your own Faith
http://en.wikipedia.org/wiki/Silence_(novel)