Nerva Julius Caluades (ネルヴァ・ユリウス・カルアデス, Neruva.Yuriusu.Karuadesu) is the Imperial Prince of the Reim Empire. He is the owner of the Djinn Shax. He is a Dungeon Capturer, having captured one Dungeon, and one of Scheherazade's King Vessel's. During the past three years he's been committing terrorist acts across the world, based on his actions and due to carrying Metal Vessel he has become one of the three most wanted criminals in the world.
Nerva is of average height. He has light colored, shoulder length hair that curves in the front along with a vine crown. He also has small thin eyebrows and a large rectangular shaped nose. He wears a black and white robe. He also wears a bracelet on his left wrist.
Nerva is an arrogant person. He thinks nothing of other countries, only about the expansion of the Reim territory. He also thinks low of the Fanalis Corps of the Reim Empire, even calling them the slave proteges of the Alexius Family.
Nerva is in the Reim Empire talking with Ignatius Alexius, and Scheherazade about war. He says that they can't avoid war with the Kou Empire and also says that the Reim Empire territory will expand even more. When the Fanalis Corps comes in, he calls them the slave proteges of the Alexius Family. He is then frightened by a member of the Corps, Lo'lo'.
When the Reim Army reaches Magnostadt, he is with Ignatius and Scheherazade in the Reim Empire Capital, Remano. When Reim's soldiers are not able to break the Borg, Scheherazade tells Nerva and Ignatius that there's no need for their Metal Vessels and asks them to believe in Reim's people.
He seems terrified when Matal Mogamett launches highly destructive, genocide attack towards Reim's people and when Mogamett is about to do it again. He is surprised when Fanalis Corps' members come to stop it. Nerva then watches Aladdin's power demonstration. He calls out Scheherazade's name and she confirms that he's a real Magi.
The Seven Seas Alliance has appeared and is attacking the Medium when Ignatius, Mu and Nerva appear. Both Mu and Ignatius are in their Full Djinn Equip, but Nerva is watching from the distance, holding his Metal Vessel with an insecure aspect. Two soldiers say that he should do the Djinn Equip as well, but Nerva tells them to shut up as he still cannot use his Djinn Equip.
Three years after Sinbad forms the International Alliance Julius goes into hiding with his Djinn Shax and Metal Vessel, causing him to become one of the three "world's most wanted" criminals. Yunan reported to Alibaba that there were rumors Julius was performing terrorist acts around the world; the Magi further note that "terrorists like Nerva appear" from time to time.  Nerva loss miserable in the election; that's why he left from the Reim Empire.  According to Judar, he has Nerva cause trouble with him in Rem Empire as part of Nerva's rebellion when Judar couldn't find Hakuryuu. Nerva is angry that Judar had abandoned his noble rebellion and then force himself and his men to toil the fields of Judar's homeland. 
When Judar and Aladdin went to find their 5th comrade, Hakuei Ren was unable to join them, so Nerva was chosen as the 5th comrade to join Alibaba, Judar and Aladdin to the Sacred Palace.  Because of Nerva's Rukh has fallen into depravity, his Rukh was never rewritten by Sinbad. 
Over at the Kou Empire's Paimon Dungeon site, Nerva and Arba observe Morgiana's group protecting the people from the angels. Nerva wonders why everyone didn't come to their senses once the rewriting on the Rukh has canceled. Arba explains to him that they still remember the feeling to return to the Rukh. While Arba has a serious reflection on the state of matters, Nerva changes the topic and calls her out for deceiving him with her young appearance. He calls her an old hag and compares Arba to Scheherazade. Nerva calls the people emotionally compromised. 
Shax is the Djinn that Nerva obtained when he conquered the 44th Dungeon. Currently, nothing is known about what kind of Djinn Shax is. Nerva's Metal Vessel is a sword.
- Djinn Equip: Nerva has stated that he still cannot use his Djinn Equip. Furthermore, Judar states Nerva cannot perform a full body Djinn Equip. 
Nerva is shown to be respectful of Scheherazade, as he saluted her when she walked into the room he was in.