Seimei Kikan

"At the sea for a thousand years, and at the mountains for a thousand years, breathing the wind and drinking pure water, he passed the training of a Sennin. Enduring it all, he gained the Life Return. Humans are able to, from the hair on their head to their intestines, their toes, even to their most minute hairs, to concentrate their senses and stretch them to their limits, making it possible to control every part of their bodies." Life Return is a technique known only to CP9 members Kumadori and Rob Lucci. Given Kumadori's flamboyant nature, the parts about a thousand years at the sea and mountains, are likely exaggerated. In the FUNimation-dubbed Unlimited Adventure, this technique is called Rebirth.

He demonstrates this when he was able to eat all the food within a giant refrigerator, digest all the food and most of his body fat, turning him super-skinny, then absorb all the nutrients in the food turning him back to his original size. He also uses Life Return to use his Hair Bind, in which he controls his hair to trap his opponents or form hands to perform Shigan with.

Somehow, Rob Lucci also knew and utilized Life Return. He only used it in conjunction with Kami-e to make his half-leopard form smaller and more maneuverable. It is unknown how Lucci was able to use Life Return, and if he has the same level of mastery as Kumadori, as he is yet to display it.

Kumadori

 * Kami Shibari (髪縛り): Kumadori lengthens his hair and manipulates it to bind his opponents. In the Viz Manga, this is called Hair Bind.


 * Haru Gin Jou (春・吟・情): After catching his opponent in Kami Shibari, Kumadori aims his staff at his opponent for a finishing blow. He attempted this at Nami.


 * Yana Gin Jou (柳・吟・情): Same as Haru Gin Jou, aside from the name. He attempted this at Chopper.


 * Shouka, Kyushu, Moto Douri (消化吸収): Kumadori uses this technique to return to his normal size body fat after eating all the food in the refrigerator in which Chopper had locked him in. In the Viz Manga this is called Digest, Absorb, Return to normal.


 * Shishi Shigan (獅子指銃): Rather than using his own fingers for Shigan, Kumadori shapes his hair into the form of hands and repeatedly uses the fingers of said hands to rapidly jab the opponent, similar to Lucci's Shigan "Madara", but less powerful. In the Viz Manga, this is called Shishi Finger Pistol.

Rob Lucci

 * Seimei Kikan: Kami-e Bushin (生命帰還　紙絵武身): Using Life Return, Lucci makes his half-leopard form smaller, lighter, and possibly increasing his speed. At any rate, he is much more agile in this form, and harder to hit - as opposed to his hulking normal half-leopard form. In One Piece: Unlimited Adventure (dubbed by FUNimation), this is called Rebirth: Sketch Form, and in the Viz manga, this is called Life Return Paper Art Fighting Form.


 * Seimei Kikan: Kaijo (生命帰還　解除): Lucci uses this while in his smaller half-leopard form. It cancels his Seimei Kikan: Kami-e Bushin technique, and returns to his larger, stronger half-leopard form. in the Viz Manga, this is called Life Return Release.

Trivia

 * In One Piece, there have been other characters who controlled their bodily functions similar to Life Return. Urouge is able to greatly expand his muscle mass instantly; Boa Sandersonia and Marigold can both manipulate their hairs into snake-like creatures; Onigumo can grab swords and fight with his hair; Speed Jiru appeared as a plump person at times, but slim at others. It is unknown if Urouge's, Onigumo's and Jiru's abilities stem from Devil Fruit powers or not, but the two Gorgon Sisters already have Devil Fruits that do not involve hair-manipulation powers, so it is more likely they are using something similar (if not the same) as Life Return.
 * For some reason in the anime, when Tony Tony Chopper roared in Monster Point, Kumadori couldn't control his hair temporarily and it froze where it was before returning to him; it was as though the roar frightened Kumadori or even the hair itself.