Hi,

How easy is it to register a tsuushoumei (alias) at City Hall?

Some quick surfing turns up http://www.moj.go.jp/NYUKAN/nyukan02-01.html
(showing where it would appear on your gaigin card), but there are also
some local authorities who seem to want proof that you are actually using
the alias.

I can see why (mainly to stop people registering silly names) but won't it
be a Catch 22 situation to try and get an alias accepted in any official
context without the proof that it belongs to you?

Also, it is possible to change your alias after you register, or does it
become absolutely fixed?

I haven't come to Japan for any period that would require the alien
registration card before, so I'm not able to ask the authorities myself; it
would be great to hear from anyone else who's been in this situation.