The Undersea Dragon's Palace (深淵の竜宮 Shin'en no Ryūgū?) also known as Neptune's Palace Archives is the nickname of the fortress constructed at the bottom of the sea that was designed to hold dangerous sacrists and other objects related to black arts tech that have yet to be analyzed.
It had a reputation similar to the Tamatebako of the Urashima Taro legend, in that if you open it then nothing good will happen. That is the source of its nickname.
The Japanese Government in coordination with the United Nations used the fortress to store various confiscated items. However, what was kept there were not items of any actual value, but rather items that were dangerous and difficult to handle. In reality, there were very few items that could actually be considered for practical use.
- Trioxon 245
- G'harne Fragments
In the same episode, Dr. Ver managed to escape from imprisonment inside the Undersea Dragon's Palace due to collateral damage from a battle, after which he absorbed a missile from Chris's Mega Death Quartet, thus saving Carol from the attack. Due to collateral damage from the last fight between Chris and Leiur, the structure collapsed due to the water pressure. Currently the remains are spread across the bottom of the ocean.