The Panthalassa Kingdom was a very ancient kingdom, in which the Panthalassa Clan used to live. However, the Panthalassa kingdom tried to take over the ocean, so Aqua Regina killed all the members of the Panthalassa Clan. Only three Panthalassas escaped: Kaito, Gaito and Mrs Amagi.
The center of the Panthalassa Kingdom was Gaito's castle, the residence of the leader of Panthalassa. After the kingdom's sealing away by Aqua Regina it was the home of Gaito. It was the place where the Dark Lovers and the Black Beauty Sisters were brought to life from sea creatures by Gaito. Sara, the former princess of the Indian Ocean, unlocked the castle by using the Sealing Key and lived with Gaito thereafter. In the same castle the princesses of the Arctic and the South Pacific Ocean Noel and Coco were imprisoned. It is impossible to located the castle because it is always moving around the ocean or it will disappear when the black mist cleared away. After the castle's destruction and the death of Gaito the kingdom officially came to an end.
Inside the Castle
Inside the castle, it is dark and the inside is mostly black. There are also different rooms in different part of the castle-
- The throne room- this is where Gaito's throne is and the glass tanks that kept Noel and Coco prisoners with several other tanks for the other remaining princesses if there were captured.
- Gaito's room- this is where Gaito goes when he wanted to be alone or if he wants to be with Sara. It has a sofa where Gaito would sleep on Sara's lap.
- Bathing room- There is a large pool that is covered with some rose petals. There is a dragon-like statue that pour water from its mouth.
- Sara's room- Sara's room has a fancy bed and a some furniture in it. There is also a large mirror on a wall above a drawer where Sara kept her split orange oyster.
- A unknown room- It a room where Sara kept Tarou Mitsuki in for him to play the piano forever. It has a black piano and it has a big glass window with no currtins. Sara would visit that room to express her hated to Tarou.
- The ball room- the floor is an ocean-color blue with a rose painted on it. The stairways are ocean blue too and there is a black piano. This room was an illusion but it could have come from the real castle. The ball room is the only room that has a different color other then black.
- Mirror room- A dark room that is filled with mirrors. This is where Lucia was traped in and Gaito tries to deceive her that he was Kaito and that her friends won't come to save her.
After the death of Gaito and the end of the kingdom there were only two Panthalassas left: Kaito and Rihito. They, however, are the only known members of the Panthalassa Clan that do not wreak havoc, instead, they saved the world. It is unknown if any of the two plan to revive the kingdom.