How might Japan be affected by all this? Their division between the British backed Republic in the South and the Russian backed (although it was half-hearted) Shogonate in the North from the 1860s to the 1900s was a tense period for the country. The demonization of the Emporer in modern Japan and the rise of several new cults to fill the religious vacuume is interesting to read about. Seriously, Japan's religious nuts are just plain weird, just be glad they hate violence.
The US had some interest in Japan at that time, namely in trade agreements and influence in the east, so they might've tried something similar to what the British and Russians did were it not for the Civil War and a refocus towards the Western Hemisphere. And the New Religious Movement can definitely get creepy from time to time. Have you seen the 骨の場所? That's literally a building made entirely out of the bones of its followers to serve as a weird hive-mind thing that reveal information to churchgoers and directly speak to the caretakers of that place as revelations from the Yomi World.