I saw when i was in Japan a various billboards marking a 25 hour service I thought it was some kind of mistake but apparently they call 1 am the hour 25...I think I saw it in Okinawa
It’s more than just 25, they often go to 29, to indicate 5am. They do this to make it clear that it is an overnight service starting in one calendar day and terminating in another. It’s not just a simple substitute for “1 am”.
Now that I’m a morning person, the same concept of 5am semantic days still works perfectly. The day begins about 20min before my alarm.