It's believable if you don't believe in Christianity i guess. For instance, it's possible that Jesus came to a 'near death' state on the cross, and they mistook it for death because of their poor medical knowledge at the time. He was then buried in a cave of all places, not underground, but a 'CAVE'. Caves don't always have just one exit, and besides, all they did was shove a big 'round' rock in front of the cave entrance. Even if he couldn't find an alternative route out (After waking up and pushing the lid aside), he might of been able to roll the stone away a little by pushing against the cave wall with his feet.

Then due to the fact he almost died, he might of fled the country. And somehow ended up in Japan, where after assuming he was safe, because everyone looked so different, and the Romans probably hadn't got there (Don't forget the Romans held most of Europe, which would explain exactly why he fled so far), he decided to settle in and live the rest of his remaining life.

Afterall, how can you believe a book which has been reproduced a billion times. I would like to see the originals really, and even then, because it's written by hand, it could of been done by anyone. If it was written in letters that say, give off an eternal flame on the other hand, it's more believable that it's been done by god or someone related to him in some way. Why make it so that anyone could of done it? O.o

So, if you arn't a Christian and you don't believe in Religion, and that Jesus was a fraud and the Bible is just a get rich scheme by someone who decided that writing a book on our creation and a higher being would make a damn good book and a good best seller, then indeed this story about him living and dying in Japan may well hold true to you! =P