Sending mail in Japan?

Question:

Hi, I am asking in behalf of my friend.

So while in Japan, she sent a fanletter to her favorite girl group. Checking the artist's website, the website indicated that the address for fanmail only included the postal code (just numbers). This surprised me and my friend because it's our first time to know that only postal code is enough (without street number, etc.). She asked some Japanese and they said that maybe, since this is an artist's agency, the code is "registered". So my friend sent the letter through her university post service and the personnel said if the postal code is indeed not registered, then the mail will be sent back to my friend the week after. Several weeks have passed and my friend has not receive her original mail yet.

Is it now safe to conclude that her mail was sent safely to the artist/address?

Or could it be that it got lost when it was being sent back to her?

Ideas?

Answer:

your friends are correct: famous companies, hotels, and in this case agencies are registered and a street address is not necessary

was it received? most likely.
will she get a reply? depends on what she wrote, the number of fan mail they regularly receive, the artist in question, etc.

In all cases, the agency will screen the mail to eliminate the weirdos, the sick and the obscene. Some artists make a point of responding to every letter they receive but that is not the norm. In general, a "generic" response is sent and this is done by a secretary or an employee of the agency and would likely include an autographed picture or something fairly standard. In rare cases, the artist themselves may review the fan mail and respond but do not set your hopes up...