Kaima Form

This technique, developed by Amachi due to Orochimaru's initial interest of creating the ultimate underwater ninja, drastically changes the user's appearance, giving them green scale-like skin, fins, and gills.

Development
Isaribi was one of the earliest Land of the Sea villagers abducted for the experiments, and became the only known surviving prototype. Eventually, Orochimaru cancelled the project out of disinterest, but Amachi managed to finalise it against his sponsor's abandonment, applying the process onto himself.

The experiment left parts of Isaribi's body permanently scaled, and Amachi falsely promised that he can return her to normal, but later confessed that he has no cure for her, and instead plotted to dissect her once he is finished using her. Agents sent by Konohagakure believes that Tsunade will be able to reverse Isaribi's modifications.

Usage
The transformation can also change the user's eye colour, as seen in Amachi's case. This form gives them supreme fighting skills in the water, as they can move through the water much faster than normal, as well as giving them the ability to breathe underwater. Also the scales used in this form have a steel like quality that can stop a kunai. Amachi also demonstrates that he can shoot the scales as a weapon.

Trivia

 * Kisame Hoshigaki has demonstrated various traits similar to that of the Kaima form, despite not undergoing the experimental surgery, such as transforming (when merging with Samehada), swimming freely at high speed and even breathing underwater.

Forma Kaima