Akihito will not be the first Japanese emperor to abdicate. You might want to look into the coronations of previous Emperors who succeeded a still living predecessor to find out if the ritual was amended or not.

There is in this case no need to look abroad, just back in history to find the answers.

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: In 1936 the UK parliament also passed a one
: time only law, so it is not unprecedented or
: unique to Japan. I suppose one could argue
: that it maintains the idea that abdication
: is an exceptional event rather than a
: "normal" part of the system.
:
: As for the Shinto ritual, I believe you are
: correct. Again to cite a foreign example, I
: suppose it is analogous to Pope Emeritus
: Benedict's resignation. Pope Francis became,
: according to Roman Catholic theology,
: Christ's Vicar on Earth even though His
: previous vicar is still living.
:
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:
:
: --Previous Message--
: The expectation is apparently that the
: Emperor
: will abdicate in favor of the Crown Prince
: at the end of 2018.
:
:
:
:
: http://www.japantimes.co.jp/news/2017/06/09/national/diet-enacts-one-time-law-allow-emperor-akihito-abdicate/#.WTszj8ZVhHw
:
:
:
: Strange to have a one time law.
: I wonder how the Coronation of the next
: Emperor will be effected when there is a
: living former Emperor. Isn't it a part of
: the ritual that the Emperor enters a special
: tent or building, where he puts on the
: Imperial costume and the goddess Amaterasu
: takes her residence in the Emperor. (This is
: a Shinto ritual.)
:
:
: