He was first mentioned by Sakazuki when the Fleet Admiral was discussing plans to deal with Luffy and Law. Due to his mission and actions he can be regarded as the secondary antagonist of the Dressrosa Arc.
Issho is a blind man with only the whites of his eyes showing, though he is usually seen with both eyes closed. He has an X-shaped scar centered on the left side of his forehead that stretches over both eyes. He has short dark hair, a mustache, and a beard. He seems to be very tall, a trait shared with other admirals.
Issho sports the standard marine coat with his personal clothes underneath. While previous admirals and high-ranked marines wear the conventional suit and tie underneath their marine coats, Issho wears a light-purple yukata held up with a dark purple belt, all underneath a purple cloak, matching the color in his alias. Issho wields a shikomizue (a Japanese swordstick) that doubles as a cane for his blindness, and also wears geta sandals. He has white bandages wrapped around both of his forearms, with handguards on both hands.
Issho appears to be a reasonable man that is very trusting of people, as seen when he believed that he kept on losing at roulette purely by chance. The moment he was told that he was being cheated and that the swindlers tried to kill Luffy for revealing their trickery, he retaliated mercilessly and believed that being blind spared him from seeing the corruption in the world.
He is also responsible about collateral damage he inflicts, as shown when he compensated the shop owner for the damages he caused when creating a massive crater to attack the swindlers. He appears to follow his own ideals instead of adhering to the Marines' doctrine of Absolute Justice. However, he still follows the law, as he chose to spare Caesar Clown simply because he was a subordinate working under Donquixote Doflamingo, although he can understand that Doflamingo could be up to something and desired to investigate further into the problem if it were not for the law and lack of solid evidence.
He is rather modest, as he barely commented on the remarks Doflamingo and Law made on his formidable reputation and display of power respectively.
During the first time he was seen in battle, Issho was shown to be willing to use excessive force as he summoned down a meteor to attack both Law and Doflamingo. Doflamingo even commented that he does not hold back.
He exhibits concern about the safety of innocent civilians more than his desire to arrest and punish criminals, unlike Sakazuki.
Despite his responsible personality, he seems to enjoy gambling and is not entirely serious with his duties, as he was playing roulette even when he was supposed to be apprehending Luffy and Law.
Another trait Issho displayed is his ability to remain calm. Even when one of his own meteorites was sent flying back at his ship, he was calmly slurping a bowl of noodles acting as if nothing was happening while his whole crew was in panic, even commenting on his choice of timing for a meal.
Marines
As an admiral of the marines, Issho is well-respected within the organization.
He seems to be trusted by fleet admiral Sakazuki, who sent him to deal with the Straw Hat Pirates' and Heart Pirates' alliance, with the two captains of the groups being a notorious pirate and a Shichibukai respectively. Sakazuki even apologized to Issho when he informed him about Donquixote Doflamingo's false resignation from the Shichibukai.
Shichibukai
Issho revoked Trafalgar Law's Shichibukai's status when Law declared an alliance between him and the Straw Hat Pirates. He then cooperated with Donquixote Doflamingo to defeat him. Even though he clearly understood that Doflamingo was up to something, he followed the law as he had no further evidence. Doflamingo arrived to Green Bit, alongside Admiral Issho and his battalion of Marine soldiers. In front of the Marines, Doflamingo immediately declared Caesar as his subordinate, thus drafting the rogue scientist into his crew while pardoning him for his crimes.
Having allied himself with Doflamingo, Issho proceeded to attack Law and the Straw Hat Pirates. Issho has shown great disgust in working together with Doflamingo. When helping Doflamingo fight Law, Issho purposely tried to harm him in the process. Doflamingo shows very little respect towards his high ranking status, and enjoys being able to manipulate him for as long as possible.
Having allied himself with Doflamingo, he proceeded to attack Law and the Straw Hat Pirates. However, Issho revealed that he dislikes the Shichibukai system and plans to end it, despite being willing to help Doflamingo in defending Dressrosa for the moment since the safety of the country was a priority.
Enemies
Pirates
As a marine, he views pirates as enemies, although he is more flexible than most and able to look past them and see their good qualities. He was willing to acknowledge Luffy's character for his help with the swindlers, and felt obligated to fight him because he considered it "biting the hand that feeds him". However, he puts the civilians' safety above the pirates' arrest. When he realized that he was being cheated by some of Doflamingo's underlings, he quickly took care of them.
Revolutionaries
Due to being an officer in the Marines, he is an enemy of the Revolutionary Army. As such he and his battalion engaged Sabo to capture Luffy. He personally clashed with Dragon's second-in-command. Despite this opposition he confesses to Sabo it is not possible for the military to stop Doflamingo and leaves the Heavenly Demon's defeat in the control of the pirates.