Sinbad is a tall, attractive man with tan skin and a muscular build. He has golden eyes and very long, purple hair tied in a ponytail. He wears floor-length purple and white robes, a white turban with feather decorations, and pointed red shoes. Sinbad also wears a lot of jewelry, most of which are actually the Metal Vessels (bangle, necklace, ring, etc.) he's collected over his years of dungeon diving, though he has had his hoop earrings since childhood. Sinbad also has a long, thin ahoge that sticks straight up. He carries himself confidently and usually has an easy smile on his face.
Sinbad is a laid back and fun-loving person. He is somewhat infamous among his subjects for getting drunk and doing outrageous things, to the point that even his closest friends don't believe him when he says that he didn't take advantage of a young princess under the influence. He can be quite a flirt and is not above using his charm to get what he wants. He tends to remove his clothes when asleep.
Despite all this, he can be serious when the need arises and is a great and honorable king who is respected and admired by everyone, especially his subjects (whom he seems to consider a sort of extended family).
Though he does altruistic deeds for other people seemingly without thanks, later it is revealed that he helped Alibaba Saluja, Aladdin, and Hakuryuu Ren because they represented powerful potential allies in his battle against Al-Thamen. When talking to Ja'far, he realizes that he became a sly person after accomplishing too many things and is now the person he never wanted to be.
He was born and raised in Tison Village of the Parthevia Empire. When Yunan and others sensed his birth, Yunan called him a Miracle. When Sinbad was 14, he captured his first and the world's first Dungeon, which was summoned by Yunan and in there his father lost his life. Since then, he has captured 6 more. It seems that having more than 7 Djinn is not allowed in this universe, because now neither he nor any members of his Household are allowed to enter Dungeons. Sinbad has also sailed across the world's seven seas, hence his nickname: Sinbad, the High King of the Seven Seas, and founded his own country, Sindria.
In his teen years, Sinbad trained with the Yambala Gladiators, during which he learned how to use Magoi Manipulation, which took him a year.
During his journeys, he recruited all of his future Kingdom's Generals. The five who are actually permanent residents of Sindria are Drakon, a former officer in the Parthevia Empire who began as Sinbad's enemy, Hinahoho, an Imuchakk warrior from the north, Ja'far, a young assassin who was hired to murder Sinbad, Masrur, one of the Fanalis Champions of the Reim Gladiator Colosseum, and Yamraiha, an ex-student of Magnostadt's Magic Academy. Sinbad also befriended Sharrkan, Pisti, and Spartos along the way, though these three are technically still members of other nations.
Sinbad has mentioned that the former King of Balbadd, Rashid Saluja, taught him many things, which included how to run a country. However, Sinbad didn't truly understand the responsibility until after he experienced a certain battle in which he hurt Sindria and its residents. He lost someone special in the conflict, much like the situation between Alibaba Saluja and Cassim. Rashid Saluja also gave him a sword, which he later passed on to Alibaba as an encouragement to pull himself together after he lost his way.
He has a bad history with Judar and Al-Thamen. Sinbad has conquered some of the Dungeons that Judar raised, and fought with him on multiple occasions. His hatred of Al-Thamen is such that he kills all the members that he faces and crushes their doll forms after their defeats with no remorse. He revealed to Ithnan that somewhere along the line, he halfway "fell into depravity", which lets him use both white and black Rukh, albeit at a heavy price.