I found this out when buying a Japan Rail Pass for a trip a few years ago, blew my mind.

https://www.japanrailpass-reservation.net/ only works 4:00–23:30 Japan time.

This is especially funny since the JR Pass cannot be purchased by residents of Japan.

I've also had issues topping up my (virtual) Suica card late at night before.

Yeah this is probably downstream of the fact that if you visit any of the individual JR sites from the expandable map at the bottom, you'll discover they're all down at this time as well. Let's scrap the website and make a staffed phone line or fax machine with operating hours.

Considering the state of japanese IT, there is probably a person typing each reservation from the website into a 1980s mainframe.

After receiving the orders that were actually printed from an Internet Explorer 6 only website, and faxed over from another office before being re-scanned in along with a barcode that usually failed to make it over the fax, hence the need to hand-type things. True story (not for JR specifically, but circa 2013)