Precedence of Emperor of Japan compared to European monarchs
This is meant as a respectful technical question. As the Emperor of Japan is not a Christian monarch even though he is the sole surviving reigning "Emperor" in the world is he really considered higher in precedent than a European King or Queen? In a hypothetical room of monarchs or if they met on neutral ground would he take seating or other precedent over others?
In terms of precedence the all monarchs are on equal footing. What they use to determine precedences is how long they have been reigning, and the Emperor of Japan came to throne in 1989. Monarchs do not bow to each other, and no European king or queen would bow to the Emperor of Japan. In term of precedence the King of Thailand is considered the doyenne of world monarchs as he came to the throne in 1946, followed by Queen Elizabeth II who came to throne in 1952. Queen Elizabeth is by far the most famous and has the grandest trappings.
So in a hypothetical meeting, they would be seated based on how long they have reigned. I believe that the funeral of King Boudin of Belgium had the emperor therm, it would be interesting to see how he was seated in comparison to say Queen Elizabeth.
Looks like I am answering my own question. I found a picture at the funeral of Boudin where all the monarchs were seated together and Queen Elizabetg II had the senior most place and not the emperor, so it looks like the rank by length of reign and not emperor trumping king/queen.