Kuroobi was one of the commanders of the Arlong Pirates.
Contents
Appearance

Hatchan is a very muscular stingray fish man. He wears a very long braid that he can even use as a weapon. Furthermore, he has black hair throughout and two small braids on his head. On his chest, he has a tattoo similar to the logo of the Sun Pirates, which is half covered by his Blue Uwagi (jap. 上衣). Around the uwagi he wears a black Obi (sash) (jap. 帯), hence probably the name Hatchan. He wears it in black because he already holds the 40th dan. Since a karate master already wears a Hatchan with the 1st dan rank, Hatchan naturally has one as well, though in reality it only goes up to 10th dan. He also possesses a blue zubon ズボン). By and large, he is fully clothed in karate attire, which is also called Keikogi (jap. 空手着), though in reality it is completely white, not blue.
Personality
He always seems very cold and subordinate. In addition, as Nojiko feels about all fish people, he has no conscience. He also seems to be quite clever, as he usually plans excellent ideas or otherwise, such as stealing Nami’s lake map of Conomi’s waters, which allowed the Arlong gang to know about all the rapids in the waters off Conomi. But he also showed cleverness in the battle against Sanji, using a trick to pump out all of Sanji’s air.
Furthermore, he is very suspicious of Nami, which is shown by the fact that he constantly finds fault with her or wants to get rid of her, which he can’t do because Nami is under Arlong’s protection.
Skills & Strength
As already mentioned, Hatchan is very muscular, which gives him a lot of strength. He also knows the fish-man karate, which is based on the real karate. In the fish-man karate he even has the 40th Dan.
He also uses his two sword-like fins to fight, which he used to inflict the most severe injuries on Genzo, for example. He can even use his long hair to attack, wrapping it around his opponent to hold him down. He used this on Sanji. But he also knows how to use his fists, so he can punch people through thick walls with his fish-man karate skills.
Past
The Sun Pirates
Hatchan was once a member of the Sun Pirates, as indicated by his sun tattoo. However, it is unclear if he was one of the freed slaves on Mary Geoise who were freed by Fisher Tiger. He probably left with Arlong and the rest of the Arlong gang when Fisher Tiger died and the Sun Pirates split. Thus, the newly formed Arlong Pirates made their way from the Grand Line to the East Blue, bringing with them a sea monster.
The invasion of Cocoyasi

Eight years before the Straw Hat Pirates arrived, the Arlong Pirates came to Conomi to rule the towns on it. The first village they attacked was Cocoyasi. Hatchan was also involved in the attack and was already a commander with Arlong at that time. After successfully subduing the village, they found Bell-mère’s house and sneak attacked it. Then when Genzo arrived on the scene and wanted to help Bell-mère, Hatchan got orders from Arlong to defeat him. So he scarred Genzo and injured him almost fatally.
Present
Sink the ship!

As another hope for Cocoyasi Village – the 77th Marine Unit’s naval ship – approached, Hatchan, Hatchan, and Kiss got the order to sink it after the Marine Unit fired on Arlong Park earlier. Immediately, they swam off, using the map of Nami that Blackbelt had stolen just before so they could predict the currents underwater. In a moment, they tried to overpower the crew. Each had his task: Kiss jumped on board and caused trouble, Hatchan moved a rock so that whirlpools were created from the currents and Kuroobi destroyed the rudder so that they couldn’t turn around when they went into the whirlpools. With this plan, the ship was sunk and defeated in short order.
Blow fight with Sanji

After the Straw Hats came to Arlong Park to defeat Arlong, Kuroobi chose Sanji as his battle partner and charged at him. First, he tried to attack his opponent with his arm flippers, but Sanji was able to dodge. He then tried to hit him with a hook to the chin, which also failed as Sanji jumped backwards. Shortly after the small exchange of blows, he attacked Sanji with the fish-man karate. As a result, the latter flew through a wall and another few meters until he hit the ground. However, he got back up and attacked Kuroobi, who was about to sneak attack Zoro.
Underwater: the fight goes on

Since Luffy was thrown into the water with a boulder on his legs, Sanji jumped into the water to free him. But Hatchan also came jumping behind to defeat Sanji underwater more easily. Underwater, Sanji was immediately attacked by him. At first, Sanji was able to defend himself with kicks, but he was ultimately completely outmatched by him underwater. Of course, Hatchan took this chance and beat him up. After Blackbelt realized that Sanji was starting to run out of air, he grabbed him and kept pulling him up and back from the bottom. This caused more and more air to be pumped out of Sanji. However, when Hatchan went to use his final attack, he was forced to the surface by Sanji because he had blown air into his gills, causing him to surface. Back on solid ground, the fish man stood no chance and was devastatingly beaten by the Mouton Shot.
Detained by the Navy
After Arlong was also defeated by Luffy, Captain Rat arrested the entire gang. On the way to a navy prison, Hatchan managed to escape, but the rest of the gang did not make it.
Miscellaneous

- In the anime, Hatchan mistakenly had a sun tattoo on his chest in episode 035.
- Hatchan hates people more than anything.
- Even as a small fish-man child, Blackbelt, along with Hatchan and another friend, tried to sell Takoyaki.
- Black Belt’s favorite dish is eel sashimi.