Wadatsumi

"Onyudo" Wadatsumi is a giant tiger blowfish fishman and a member of the Flying Pirates under captain Vander Decken IX.

Appearance
Wadatsumi is an enormous fishman, equal in size to the head of the kraken, Surume. He is large enough to make the giant-sized Shirahoshi looked human-sized. His round head and chest are quite big in comparison to his arms and legs. His hands are webbed. He has a big, round face, with a large mouth full of massive, round teeth quite distant from one another, and child-like eyes. He has some stubble on his chin and dark hair surrounding his head, taking the shape of a protrusion pointing upward at the top, which also covers a part of his shoulders. His whole body is also quite hairy.

He apparently wears a pair of extremely loose pants paired with a dark indument tied around his waist; and some sort of boot-like footwear.

His overall shape, size, and eyes strongly resemble that of Sanjuan Wolf's. Due to his appearance, Wadatsumi was incorrectly called an Umibozu by Usopp.

Personality
He is loyal and obedient, following Decken's every command without question. He knows what Decken wants and don't wants as he explains to Ankoro that Decken prohibits eating ships before collecting treasure.

Abilities and Powers
Due to his large size, and the fact that he is a fishman, he is extremely powerful. He shows his strength by hurting Ankoro, an angler fish several times the size of the Thousand Sunny, with a single punch, even though the punch was only intended to prevent the fish from eating the Straw Hat Pirates, and not to harm him. Also, living in the depths of the Grand Line, he is capable of breathing underwater as well as surviving the crushing pressure of 10,000 meters below sea level.

He seems to be able to appear whenever Decken calls out to him.

Fishman Island Arc
While the Straw Hats (minus Luffy, Zoro, and Sanji) were sailing through the underworld of the sea, Wadatsumi suddenly appeared from the rocks beneath the sea. He beats an angler fish with one blow to prevent it from eating the Thousand Sunny because the captain of the Flying Dutchman, Vander Decken IX, wants their treasure. On Vander Decken's orders, Wadatsumi attempts to punch Thousand Sunny, but the kraken (which had been tamed by Luffy, Zoro, and Sanji) intervenes and knocks out Wadatsumi.

When the volcano erupts, Vander Decken orders Wadatsumi and Ankoro to pull the ship away from the magma. As the water temperature rose, he and the Flying Dutchman were thrown forward.

He is later seen walking on the sea floor pulling the Flying Dutchman. Vander Decken IX asks how many years it has been that the Mermaid Princess has not replied to his letters. Wadatsumi answers that it has been ten years and the princess still has not replied, enraging Decken. He is then seen in Noah in the Fishman District where Vander Decken IX and Hordy Jones form an alliance.

After Luffy takes down Decken at Coral Hill, Decken calls out to Wadatsumi to prevent Princess Shirahoshi from escaping. Luffy beats him back with a Jet Pistol, breaking off one of his teeth.

Major Battles

 * Wadatsumi vs. Surume
 * Wadatsumi vs. Monkey D. Luffy

Translation and Dub Issues
"Onyudo" (大入道), Wadatsumi's nickname, literally means "large, bald-headed monster" or "giant". "Umibōzu", which is what Usopp incorrectly refers Wadatsumi as, means "sea bonze", a Japanese mythological spirit. Wadatsumi's name itself is derived from "Watatsumi", the name of the Japanese sea god and dragon of Shinto religion.

Trivia

 * He is the largest fishman to date and the only one so far to have no obvious fishman appearance to him, aside from dorsal fin and webbed hands, which made many fans wonder how he was able to breath underwater when first introduced.

External References

 * Umibōzu - Wikipedia article about the legendary sea monster Usopp mistakes him for.
 * Watatsumi - Wikipedia article about the Japanese sea god/dragon he is named after.
 * Takifugu rubripes - Wikipedia article about the species of fish he is.