As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WHILE AT CRUISE, THE NR 1 ENGINE OIL QUANTITY DECREASED TO ZERO WITH THE PRESSURE AT 25 PSI. THE ENGINE WAS SHUT DOWN AND THE AIRCRAFT RETURNED TO NRT. MAINTENANCE REPLACED THE NR 1 ENGINE THE EXACT PART CAUSING DIFFICULTY TO BE DETERMINED.