According to CNN:
The Izumo has a crew of 470, and with a standard displacement of 19,500 tones (24,000 tonnes at full load, according to military publication Jane’s), it is as large as the storied Yamato-class battleships which fought U.S. naval forces in the Pacific theater of World War II.
At 241 meters (791 feet) in length, the Izumo is 51 meters (167 ft) longer than the Hyuga, another helicopter carrier which was, until now, the MDSF’s largest vessel.
But beliefs that the Izumo would be used as a conventional aircraft carrier were dispelled by Defense Minister Gen Nakatani, The Japan Times reported.
Addressing reporters after the commissioning ceremony in Yokohama on Wednesday, [Nakatani] emphasized that the ship is designed to carry patrol helicopters, not fixed-wing aircraft such as fighter planes.
“We are not thinking about using this as an aircraft carrier,” Nakatani told CNN. “… The vessel can serve in a wide range of roles including peacekeeping operations, international disaster relief and aid.”