A Japanese supertanker has emerged in the Gulf of Oman after last signaling that it was inside the Persian Gulf, indicating a rare, undercover transit through the Strait of Hormuz by a vessel from the Asian country.

The Eneos Endeavor, a very large crude carrier, began transmitting its location north of the Omani capital Muscat late Wednesday, sailing east toward the Arabian Sea, ship-tracking data show. That came after the tanker’s last signal showed that it was in the Persian Gulf, north of Abu Dhabi, on Monday. The gap in its transmissions suggests the ship sailed through Hormuz without broadcasting its movements.

Eneos Endeavor had sailed into the Persian Gulf in late February to pick up crude from the United Arab Emirate’s Das Island and Kuwait’s Mina Al Ahmadi. Draft readings indicate that the vessel is nearly full with cargo.…