Simon Island is a large island that exists off the coast of Japan. The island was the home of Cozarto Simon after he left Italy and is the current Famiglia generation's base of operations.
The island is located just off the coast of Japan. It has many different areas on it that are significant to different events important to Simon. A path carved into the stone will lead people around the island. The island itself also has special defensive capabilities that are controlled by mist or desert flames. The island is capable of being concealed from normal view and that of a radar and is capable of blocking outside mental energies, such as those of illusionists.
The island has a large house built into the rock along part of the island's coastline. Enma's family resides here while fighting Tsuna and his Guardians. With the revelations of the third key, it is revealed that this is also where Cozarto lived while on the island.
The forest was the location of Koyo Aoba and Ryohei Sasagawa's boxing match. It was filled with plants that had grown since the time of Vongola Primo and had apparently tasted the blood of Cozarto and Giotto's battle. However most of the plants were blown away by Ryohei's final attack, leaving a barren field.
This was the location of Rauji Ooyama and Lambo's sumo match, found on accident while Lambo chased after a bunny. When Gokudera, Tsuna, and Reborn chased after Lambo, they fell down into a hidden cave. The large underground cave had a raised platform that acted as the ring. Rauji claimed that the structure was unstable and certain rocks were essential to its structure. Rauji also claimed that the cave was similar to the structure where the Simon Famiglia was betrayed.
The town was the site of P. Shitt and Gokudera's battle. It is a small town that was built on the island and a replica of the town where Cozarto Simon and Giotto first met, founding their respective families. After the battle finished, Enma arrived and challenged Tsuna to a second battle.
This temple-like building exists on the top of a large hill on the island with a long stone stairway leading to it. It has a large circular structure with a single spiral that sits atop it. The building is the center of the island's illusion defense system and has an altar that can control them. This is where Daemon and Mukuro had their battle.
A large underground castle built in a European style. It is located in a large cave with a winding stone path that leads to it. It has many large spirals and a throne room.