Akitsukuni

Akitsukuni (秋津国) is the second-largest of Yamatai's six main islands. Part of the Naichi archipelago, Akitsukuni is located to the east of Harukuni.

The island includes the Heian Metropolitan Area and encompasses six provinces: Izumi, Ōsumi, Kinai, Suiyōkuni, the Heian Metropolis, and the Oki Islands. The island has a population of 22.3 million as of 2016, mostly concentrated in the plains on the southern coast of the island, where the Heian Metropolitan Area accounts for 53.4% of the island's population.

Kinai
Cities in Kinai include Yamanote, Awara, Shinagawa, Miyako, Higane, Kōya, Kasukabe, and Ogawa.

Izumi
Cities in Izumi include Izumi, Nishinomiya, Washimiya, Tamura, Katsuta, Nakanishi, and Higashinada.

Ōsumi
Cities in Ōsumi include Shimokita,Taguchi, Aikawa, Tamuro, Ōsumi, and Fukuda

Suiyōkuni
Cities in Suiyōkuni include Suiyōkuni, Fujī, and Tarumi

Oki Islands
The Oki Islands are located in the Haru Inland Sea and comprise of five major islands and 73 minor islands. The largest island is Majima. Cities in the Oki Islands include Majima and Takeshima.

The Chiburijima Imperial Mausoleum, the traditional resting place for the deceased Yamataian monarchs, is located on Chiburijima in the Oki Islands.