Basics of Japanese multi-byte encodings
 
  Japanese characters can only be represented by multibyte encodings, 
  and multiple encoding standards are used depending on platform and 
  text purpose. To make matters worse, these encoding standards 
  differ slightly from one another. In order to create a web 
  application which would be usable in a Japanese environment, a 
  developer has to keep these complexities in mind to ensure that the
  proper character encodings are used.
 
 
  
   - 
    Storage for a character can be up to six bytes
   
- 
    
     Most Japanese multibyte characters appear twice as wide as
     single-byte characters. These characters are called 
     "zen-kaku" in Japanese, which means 
     "full width". Other, narrower, characters are called 
     "han-kaku", which means "half width". The 
     graphical properties of the characters, however, depends upon 
     the type faces used to display them.
    
   
- 
    
     Some character encodings use shift(escape) sequences defined
     in ISO-2022 to switch the code map of the specific code area
     (00h to 7fh).
    
   
- 
    
     ISO-2022-JP should be used in SMTP/NNTP, and headers and entities
     should be reencoded as per RFC requirements. Although those are not
     requisites, it's still a good idea because several popular user
     agents cannot recognize any other encoding methods.
    
   
- 
    
     Web pages created for mobile phone services such as
     » i-mode
     or » EZweb
     are supposed to use Shift_JIS.
    
   
- 
    
      As of PHP 5.4.0, the pictogram characters 
      used for mobile phone service such as 
      » i-mode
      or » EZweb
      are supported.