Konbu is one of the children kidnapped by Caesar Clown and treated with the NHC10 drug.
At first glance, Konbu seems like a normal child. But because Caesar Clown experimented on him and the other children, Konbu is as tall as a giant’s child. His head and body are quite pencil shaped. He has thick lips and relatively small eyes.
Konbu, along with Mocha, Sind, Uzu, and Doran, were among the first children kidnapped by Caesar, which is why they are the tallest. He fled like the other children with the Straw Hat Pirates when they accidentally showed up in Biscuits Room. When they took shelter in a cave and Sind started hallucinating due to withdrawal from the drug, the same thing started happening to Konbu and Mocha right after. As a result, the Straw Hat Pirates had to put the kids to sleep and put them in chains. However, when they woke up a few hours later, they managed to break the chains and attacked Nami and Usopp who were guarding the children. Caesar had also arrived by now and took the children back to his lab.
At the lab, the kids were supposed to get candy again, but this was prevented by Chopper, who managed to sneak into the lab, and Mocha, who came back to her senses. Konbu and the other children then chased Mocha, who tried to keep them away from the candy.
Later, the children were sedated thanks to the G5 marines and Chopper. After Caesar was defeated, Law treated the children to remove the drug from their bodies. Later, the children went on a tanker so that Tashigi and some marines could take them back to their parents.
After Doflamingo’s defeat on Dress Rosa, Tashigi informed the children that they would soon meet Dr. Vegapunk.