Amachi

is a medical ninja/scientist who is an accomplice of Orochimaru. He and Orochimaru terrorized the people of the Land of the Sea and kidnapped the citizens for their deadly experiments (including Isaribi) which included making the ultimate underwater ninja for Orochimaru. He orders Isaribi to attack ships, promising to return her to her normal form, but truly intending to dissect her once she is no longer of use. He also seems to know Anko Mitarashi as well, since she was with Orochimaru at the time. Much later, in the Sea Country arc, Yoroi Akado and Misumi Tsurugi join him as bodyguards and assistants. He planned to steal gold from a coming ship and manipulate Isaribi into attacking it. It was also revealed that he planned on using his experiments to take revenge on Orochimaru. In the final confrontation with Anko, Naruto Uzumaki, Ino Yamanaka, and Shino Aburame. He also summons the indestructible Umibozu and later transforms into a Kaima. He is defeated by Naruto's Uzumaki Naruto Two Thousand Combo and is captured by Anko's team. Upon capture, he mentioned that he didn't know a way to cure Isaribi and plotted to dissect her when she was no longer useful. Naruto grew infuriated and tried to strike him but Anko held him back, only to slug Amachi herself.

Trivia

 * In Naruto Chapter 245, page 2, right bottom image, a figure walks in the Konoha streets who looks a lot like Amachi.