First off, their meaning is actually quite easy to figure out: So as seen on the left the picture of a store close to Ebisubashi in Osaka shows for example '28:00'. Basically 24+4 so 4:00 AM.
Personally I have only seen this in Japan so far, so I got curios about it and wanted to find out what kind of reasons are behind that way of counting.
Interesting reasons
As demonstrated before one reason is that it's an easy way to calculate time frames starting the day before going beyond 24 o'clock. For example a TV show runs from 23:00 until 25:30. Now you can easily calculate that the length of the show was 2 hours 30 minutes.
So the hours beyond 24 are actually applied for things which start before midnight and go until a certain point during the night. This also counts for bars or night clubs.
Another reason is to avoid possible confusion between AM and PM. If a store has opened from 08:00 - 02:00 without using AM/PM there can be actually two meanings.
Also, the closing time of a store going into the next day will also be considered as the business day starting from the day the store opened.
Here it means: From Monday to Thursday opened until 27:00 Friday, Saturday and Sunday opened until 28:00 |
And there's also a thing about the cultural perception about the hours in darkness which should better fit into the previous day, starting with the day in the morning with the sunset.
I also read that there are other countries using that system in specific situations. Like UK, Hong Kong or China.
On the other hand there are also occasions when Japan uses the 12 hour system.
My opinion
It's surely an interesting approach and definitely easy to get used to, although it can be confusing at the beginning. Especially the reasons make totally sense to me why people are thinking that way.
If there's a connection to the previous day, use hours beyond 24! So surely, why not?