Just saying, but I think a lot of japanese lie and say their blood type is AB. I realize AB is more common there, but probably not nearly as common as represented by the people that told me they were.
Mana? Foreigners do not get it? What is so strange about it? It is just like any other superstition, astrology, chinese zodiacs, etc. Yes, i did call it a superstition, either way, the concept is not difficult in the slightest.