Since your last question was about the miniseries and not the book, I assume that this one is as well. I have changed it to reflect this.
Blackthorne's first contact with Japanese people is with the woman who is caring for him in the house where he has been put. This interaction is full of misunderstanding. For example, Blackthorne asks the woman her name and thinks that "onna" is her name when it really just means "woman."
His next interactions are characterized by his arrogance clashing with that of the Japanese, particularly of Omi. Blackthorne is an important person in his world and also comes from a world that thinks that Asians are in some way inferior. These combine to make him arrogant towards the Japanese, culminating, perhaps, in the incident where Omi urinates on Blackthorne to humiliate him and to get revenge for Blackthorne saying that he "pisses on" Japan.