Susanne, if you want a really good read and to gain a bit more knowledge of that period before isolation (albeit in a novel) you might enjoy Shogun by James Clavell. It is loosely based on a true story.
Have to agree with Tony here. I love Shogun. I've read it more times than I've read LOTR.
And I enjoyed Last Samurai.
They made a film of Shogun yonks ago with Richard Chamberlain but it was pants!
(Believe it or not, I actually carefully-worded my initial post so as not to cause offence to Christians. Before last Saturday I never knew about the 26 crucifixions or Urakami cathedral and I thought it was ironic that the US, a Christian country, rather than take out Kyoto with over 2000 "heathen" temples and shrines, should vapourise the biggest Christian cathedral in the whole of Asia!)