Due to the sudden executions and expulsions of Japan’s Catholic clergy, many persecuted Japanese Christians ended up not fully catechized. As you would expect, some of the Hidden Christians were just doing their best in the absence of training, while others went for syncretism or their own special brands of wackadoo. There’s also a tendency for modern cult leaders and occultists to try to fold Christianity into their own weird brands of belief.
So you have a town called Shingou in Aomori which, like ancient Docetists and today’s Muslims, refuses to believe that Jesus would allow Himself to be executed or would be able to resurrect. No, this town believes (since AD 1933, anyway) that Jesus’ younger brother died on the Cross, and that Jesus snuck out and went to Japan, where He died of old age and was buried, full stop. They have also designated a random grave mound as “the grave of Christ,” which is illogically topped with a cross. Info about all this was received in a Mormon-style document allegedly discovered by a village cult leader, and then handily disappeared before anybody else could look at it.
However, transcripts of the document in the local museum also detail the fate of Atlantis and humanity’s alien origins, Edgar Cayce-style.
Syncretism. Not a pretty sight.