Sind became much larger than an average child due to the experiments done on him at Punk Hazard. His head is rather big and not very proportionate to his body. He has blue hair (blond in the anime), that is unkempt and goes over his ears, he also has blue eyebrows (blond in the anime). He wore a sleeveless shirt with shorts, until Kin'emon gave all the children jackets. His jacket was light colored, with a dark colored hood, and fur at the end of the sleeves.
In a photograph held by his father, he can been seen at his normal size, which was that of an average child.
When deprived of the drug NHC10, Sind became very aggressive, brutally punching Luffy into part of the building. Otherwise, he is a normal timid child, as he was scared of Kin'emon's severed head.
When not under the effects of the drug, Sind is a boy with high hopes, as he had reassured Mocha near the beginning of being taken from his home, believing that they would be better soon and be able to go home quickly. He has also stated that he wanted to be a pirate at the age of 20, getting very excited for it.
Abilities and Powers
Punk Hazard Arc
When the Straw Hats arrived at Punk Hazard, Sind and the other children begged the pirates to save them. After being freed, he succumbed to the withdrawal symptoms of NHC10, which he and the other children were fed regularly in candy form. Eventually, Sind became very aggressive, punching Monkey D. Luffy through some pipes. The children went on a rampage until Usopp managed to knock the children out using the sleeping gas, leaving the Straw Hats no choice but to chain the children up for their own safety.
Later, when the Straw Hats had infiltrated Caesar's lab, Mocha and Tony Tony Chopper kept the wild kids from going to the Biscuits Room. When Sind and the kids finally advanced, they chased Mocha, who had taken all the candy, and attacked Chopper in his Monster Point. They soon reached the Biscuits Room and overran Nico Robin's Mil Fleur technique in their run. Mocha ran on and the kids followed after, while being chased by Robin, Nami, and Chopper. They eventually cornered Mocha and attacked her, trying to take the candy from her hands. However, Mocha ate the whole batch and Sind, among others, got mad and attacked her. Soon after, the Marines arrived and subdued Sind and the other kids, for Chopper to sedate them. Sind was quickly put to sleep.
After he woke up from his sleep, Sind ran with Nami, Robin, Sanji, the G-5 Marines, and the other children to the exit of the Building R. Soon after Law cut the entire laboratory, the gas, Shinokuni, started to seep in which scared the children. At the same time, the group joined up with Roronoa Zoro and Tashigi who came running towards them and continued to run to the exit.
The group eventually reached the exit and joined up with Luffy and his group. Soon after that, Law and Smoker reached the exit with a cart that Law meant to use for escaping the laboratory. When the rest of the children, Straw Hat pirates, Caesar's subordinates and G-5 Marines reached the exit, the survivors started escaping from the crumbling laboratory.
While everyone was escaping through the tunnel, they heard an explosion coming from Building D. The explosion caused the corridor to collapse. Law noted that if the tunnel is part of the mountain that if it collapses they will be buried alive; however, they eventually reached the exit safely due to the actions of Zoro and Luffy. Upon breaking through the exit and reaching the outside world, Sind noticed the Franky Shogun along with the other kids and the G-5 Marines. He reacted to it just like Luffy, Usopp, and Chopper (except for the female children).
After Caesar, Buffalo and Baby 5 were captured, Sind and the other children had the medicine in their bodies removed by Law. They stated their concern about Mocha's well being, but Chopper assured them of her safety by saying she will wake up soon. When they asked where Nami was and asked if she would take her home, Tashigi entered the room and stated that the Marines would take care of them now, much to their disliking. Soon after, Sind and the others gathered around the food Sanji made with bowls in their hand and drooling mouths. Not long after that, all the survivors started a party together.
When the party came to an end, Sind and the other kids were escorted by the G-5 Marines on to the tanker. While the Straw Hats were preparing to leave as well, Nami said to Chopper that Vegapunk was going to help cure the kids from the effects of the candy. As they began to leave, the Marines put up Marine banners to prevent Sind and the others from seeing the Straw Hats while saying that the Marines are justice and pirates are scum. Sind and the other kids still wanted to see the Straw Hats and told the Marines to move. The Marines responded to them by pointing their rifles at them saying that only bad kids want to see pirates.
However, the kids insisted that the Straw Hats tried to save them even though they knew nothing about them. Sind also said that even though nobody ever came to the island, they did come. However, the Marines kept insisting that pirates are always evil and that they are justice. Tashigi then interrupted them and said they are a disgrace. The G-5 Marines told her that if they did not bad mouth the pirates, they would come to respect them. Finally the Marines gave in and let Sind and the other kids say their goodbyes. They also stated that they would become pirates too when they grow up, regardless of the disapproval of the G-5 Marines gave them.
While traveling with the G-5 Marines, Tashigi informed the children that they will see Dr. Vegapunk in a few days.