Japan published its 2020 Defense White Paper today and in the section on the F-35B, the government has confirmed that the stealth fighter will operate from the Izumo-class helicopter destroyer.
By Kaijō Jieitai （海上自衛隊 / Japan Maritime Self-Defense Force） (http://www.mod.go.jp/msdf/formal/jmp/201612.html) [CC BY 4.0], via Wikimedia Commons
The paper says this is in response to the new security environment and to protect Japan’s air and sea approaches.
It added that Japanese fighters currently can only operate out of 20 runways across Japan, with the F-35B, this will increase to 45 runways.
Former Japanese Defense Minister Itsunori Onodera had told a Upper House Budget Committee session in 2018 that he had authorized the study on whether the Izumo-class helicopter destroyers can operate the F-35B.