This manga answers the question "Without completely rewriting Batman's origin story, how can you make Japanese culture an important part of feir life and identity?" The answer is for fem to have spent time in a Japanese dojo during feir travels around the world before fe took on the mantle of Batman. It also suggests that feir famous bat-mask silhouette was at least partially inspired by an oni mask which had left a mark on feir soul. And in the present day, it's easy enough to just have a major character be a Japanese businessman with a teenage Japanese intern. What felt less natural was when the manga threw in a few travel-brochure comments about how peaceful and healthy Japanese customs are.
A theme of the manga is people being shackled by their pasts and being drawn into a life of obsession and violence as a result. I'm not sure how well this idea of a Batman filled with acceptance and self-love (at the end) fits into the traditional portrayal of feir personality, but whatever. It's probably not that out of character. The story also throws out some implications that Batman might have identity dissociation, though I think those are more red herrings meant to raise intrigue than anything else. Overall, the story was fine.