On Thu, 1 Jan 1998, Angus MacSpon wrote:

(Question asking about how floors are numbered in Japan)

The following information is derived from my textbook "Japanese for Busy
People" from the Association for Japanese-Language Teaching.

As many of you probably know, in Japanese there are kanji for the numbers
1 to 10 (ichi, ni, san, shi, etc.). There is also a kanji for "kai" 
(sometimes "gai"), meaning floor. The floors are numbered as follows: 

ikkai (not ichi-kai, but kanji is written that way) - 1st floor
ni-kai (2nd floor)
san-gai (3rd floor)
etc.

And for floors below the first floor:
chika ikkai (1st basement)
chika ni-kai (2nd basement)
chika san-gai (3rd basement)
etc.

(note that there is a special exception for 3rd floor...san-gai not
san-kai)

A building with 3 normal floors and 1 underground one would have 1st
basement (chika ikkai), 1st floor (ikkai), 2nd floor (ni-kai), and 3rd
flor (shi-kai). So there is no floor labelled "G".