Japanese name: ダーク・キングダム Romanized name: Daaku Kingudamu
Queen Metalia (クイン・メタリア; Kuin Metaria)
Queen Beryl (クイン・ベリル; Kuin Beriru)
Jadeite (ジェダイト; Jedaito)
Nephrite (ネフライト; Nefuraito)
Zoisite (ゾイサイト; Zoisaito)
Kunzite (クンツァイト; Kunzaito)
Prince Endymion/Metalia Endymion (プリンス・エンディミオン; Purinsu Endimion/メタリア・エンディミオン; Metaria Endimion)
Dark Mercury (悪のマーキュリー; Aku no Maakyurii)
Mio Kuroki/Queen Mio (黒木ミオ; Kuroki Mio/クイン・ミオ; Kuin Mio)
From: Bishoujo Senshi Sailor Moon
The Shitennou (四天王), or the Four Heavenly Kings, are loosely based on the gods found in Buddhism. Unlike their anime counterparts, the live-action Shitennou are acknowledged as Endymion’s friends and guardians from the past.
Aside from Endymion, Dark Mercury and Mio, the Dark Kingdom names are inspired by minerals. An example is that Jadeite’s name is derived from a form of jade known as jadeite.
In Greek mythology, Endymion was a beautiful young man that Selene, the goddess of the moon, loved.
Mio’s surname “Kuroki” (黒木) literally translates to “black tree”. She took on the form of a dark, plant-like youma in the Special Act.
The location of the Dark Kingdom is a bit vague. It appeared to have caverns and a forest, though. The new Dark Kingdom, established by Queen Mio, was at an abandoned amusement park.