These metal seals are placed over the left sided bolt on the rear number plate, with a single kanji representing the location in which vehicles are registered.
At present, there are a total of 106 different issuing municipalities covering the 47 prefectures, territories and metropolises of Japan, each with their respective names displayed in Kanji. Tokyo, being the largest urban area in Japan, has a total of five: Adachi, Hachioji, Nerima, Shinagawa and Tama, as shown in the image below.
While vehicles are categorised from 0-9, privately registered vehicles utilise numbers 3 and 5 only. Standard cars with a maximum capacity of ten persons will display 3xx, with small and kei cars displaying 5xx.
In addition, cars utilising only two numbers for classification can still be seen today, e.g. 3x and 5x. These vehicles were registered prior to the 14th of May, 1999, with the exception to kei cars which changed to a 3-digit classification system in January 2005.
The hiragana symbols to the left of the number plate specifically identify the type of use for each vehicle. Privately owned vehicles of small and standard cars use the following:
While kei cars use the following:
NB: Vehicles identified with the hiragana わ are reserved for rental vehicles only, while non-Japanese character based number plates (E, H, K, M, T and Y) belong to users of the U.S. army based in Japan.
Split into two groups of two-digits with a hyphen in the middle for ease of reading. Numbers range from 1 to 99-99. Numbers not used in personalised number plates are replaced with a centered dot. With the exception to U.S. Army vehicles, numbers 42 and 49 are prohibited on the last two digits due to their connection with death.
Vehicles with a yellow number plate are reserved for kei cars with an engine capacity of 660cc and below, with small and standard vehicles possessing a white plate.
Other colours include, but not limited to, blue; reserved for diplomats from consulates and embassy staff, and green, specifically for commercial vehicles - such as taxi's.
Temporary number plates are reserved for vehicles whose plates are missing, the shaken has expired or have not been registered as of yet. Clearly visible with a thick diagonal red line across the plate.