An ANA All Nippon Airways Boeing 777-200, registration JA703A performing flight NH-37 from Tokyo Haneda to Osaka Itami (Japan) with 274 passengers and 11 crew, was climbing through FL150 out of Haneda Airport when the crew stopped the climb due to the cabin not pressurizing properly. The passengers oxygen masks were released. The aircraft returned to Haneda for a safe landing about 25 minutes after departure.
The airline reported the captain received an indication of a possible malfunction of the pressurization system, released the oxygen masks and returned to Haneda.
Japan's Ministry of Transport reported the crew received an alert regarding an anomaly in the cabin pressurization system.
Passengers reported there was a bang, probably from the left hand engine, during takeoff, about 15 minutes later the oxygen masks came down followed by an announcement by the captain indicating an emergency descent.
On Aug 13th 2017 the airline reported maintenance found a fractured duct running through the left main gear well under the main wing, which permitted cabin air pressure to escape.
The occurrence aircraft is still on the ground about 25 hours after landing back.