Historically, Japan is notorious for the application of the "gotcha" rule - aka the "HIP" - or the "Higher Intermediate Point" rule.

As mentioned, an Int'l. S/O occurs when the S/O exceeds 24 hours.

The fare about which U speak carries the fare basis of C1234 and is $1760. This fare DOES allow "unlimited S/O" with an ********.

Astericks denote the fine print - exceptions
to the "unlimited S/O" rules.

Unfortunately, they "gotcha". The astericks
in this case state that both HIP's and MPM's(Maximium Permited Mileage) will apply.

To avoid the HIP, simply depart w/in 24 hours, or contact a consolidator which may be able to offer U a tkt where the HIP may
not apply or its burden may be reduced.