Here are a few of the mythic places found within the Shinto/Japanese myths. They are arranged by altitude as best I can. Beginning with heaven and descending through the Earthly realms before plunging into the shadowy underworld of the dead.

Takamagahara

(also Takaamahara, Takanoamahara, Takamanohara, Takamagahara)
(Japanese: 高天原 （たかあまはら、たかのあまはら、たかまのはら、たかまがはら）

Literally “High Heaven’s Plain” but often translated as the “High Plain of Heaven”. This is where the kami live and gather.

Ama-no-uki-hashi

Literally the “Floating Bridge of Heaven”. It is the bridge that connects the Earth to the Takamagahara. In Shinto worship, the kami are invited to leave Takama-ga-hara and enter a shrine or some other purified place.

Ashihara-no-Nakatsukuni

Japanese: 葦原の中つ国
Translated: “central land of reed plains”

This is the Earthly realm where the humans live.

Onogoroshima

Also: Onogoro or Onokoro
Japanese: 淤能碁呂島 or 磤馭慮島
Translated: “Self Curdling Island”

This was the first island created by Izanagi and Izanami when they descended from Takamagahara. They built a palace, Yahiro-dono, on top with a great column in the middle.

Yomotsuhirasaka

Japanese: 黄泉津平坂

The entrance to Yomi. It was blocked by a large boulder by Izanagi when he fled Yomi.

Yomi

(Japanese: 黄泉)
The land of gloom where Izanami went when she died. Izanami rules the Yomi. It is where dead people go when they die. It is neither heaven nor hell. It is a separate place for the dead who continue on in a shadowy existence.

It is said to be guarded by horrible creatures. Izanagi followed Izanami when she retreated here. When he left Izanagi blocked the entrance with a huge boulder. Yomi is said to be underground and the sealed entrance is also said to be located in the Izumo province.

Izanagi called Yomi polluted and purified himself when he returned from Yomi. Ther purification created Amaterasu, Susano and Tsukuyomi. The reflects the Shinot association between death and pollution.

Ryūgū-jō

Japanese: 竜宮城/龍宮城

The undersea palace of Ryūjin, the dragon god of the sea. Depending on the version of the legend, it is built from red and white coral, or from solid crystal. The inhabitants of the palace were Ryūjin’s servants, which were various denizens of the sea. On each of the four sides of the palace is a different season, and one day within the palace is equal to a century outside its boundaries.