Yontoryu is a sword technique developed and used by Kaku.
As the technique's name suggest, Yontoryu is swordsmanship that uses four swords. Kaku achieves this by combining his two shirasaya katana with his Rokushiki technique "Rankyaku", which lets him create slicing air blades via kicking, thus appearing to have four blades in total. Kaku's large variation in the Rankyaku technique makes the Yontoryu a truly powerful and versatile combat style. The most prominent example of combining his two swords with his Rankyaku is the Rankyaku: Ran, that uses the two blades to stay on the ceiling while raining a flurry of air blades down at his opponent. However, Kaku can only maintain Yontoryu if he is in control of the fight; if forced on the defensive, as seen at the beginning of his fight with Zoro, he can only defend with two swords. However, when transformed to his half-giraffe form, his reach is long enough to make it largely impossible to force him on the defensive.
Upon consuming the Ushi Ushi no Mi, Model: Giraffe, Kaku further attained versatility with his Yontoryu style, by combining the increase in size and strength that he gains from transforming into a giraffe-human hybrid. His long neck also serves as a whip of sort, which he functions somewhat like a blade.
- Rankyaku "Hakurai" (嵐脚「白雷」 Rankyaku "Hakurai"?, literally meaning "Storm Leg: 'White Thunder'"): A much more powerful form of Rankyaku that is used by using both legs, it appears to cut the air in a larger area. It was shown to be equivalent in strength to Zoro's Nanajūni Pound Hō. In the Viz Manga, this is called Tempest Kick White Thunder. The kanji for "hakurai" can also be read as "byakurai" instead.
- Rankyaku "Ran" (嵐脚「乱」 Rankyaku "Ran"?, literally meaning "Storm Leg: 'Riot/War'"): After using Geppo to launch himself into the air, Kaku stabs his swords into the ceiling to stay in the air, then launches multiple Rankyaku with both legs. Each cut is smaller than a normal Rankyaku. In the Viz Manga and FUNimation dub, this is called Tempest Kick Slaughter.
- Rankyaku "Amane Dachi" (嵐脚「周断」 Rankyaku "Amane Dachi"?, literally meaning "Storm Leg: 'Circumference Sever'"): Used in half-giraffe form. In this attack, he spins around quickly in a circle while standing on one hand, using his elongated neck to gain extra momentum and spin faster, and then performs Rankyaku with both legs to create a circle shaped Rankyaku which radiates outward. The attack was powerful enough to cut through the outer walls of the Tower of Justice in all directions. It can also be used to send an enormous mass of Rankyaku at the user's opponent, to inflict massive damage. Kaku says that this is his most powerful Rankyaku. In the English version of One Piece Unlimited Adventure, this is called Rankyaku: Amane Dachi, and in the Viz Manga and FUNimation dub, this is called Tempest Kick Sky Slicer.
- Rankyaku "Kiri Shigure" (嵐脚「麒麟時雨」 Rankyaku "Kiri Shigure"?, literally meaning "Storm Leg: 'Giraffe Autumn Rain/Drizzle'"): Used in his half-giraffe form. After turning himself into a cube with Tekkai "Mushikaku", Kaku uses Rankyaku towards the ceiling with all four of his limbs. There, the vast mass of small Rankyaku blades bounce back, falling like rain on the enemy, making the attack difficult to block, to inflict continuous damage. The "Kiri" part of the name can also mean "mist". In the Viz Manga, this is called Tempest Kick Giraffe Shower.
- Pasta Machine (パスタマシン Pasuta Mashin?): Used in half-giraffe form, this is Kaku's most abnormal technique. After pulling his neck in too much from Kirin Houdai, his neck is completely gone, but his arms and legs become very long, like putting dough through a pasta machine. After saying this, he immediately named this attack and got yelled at by Zoro to not name his attacks on the spot. In this mode, he can use his Yontoryu technique to the greatest effect because of his added reach.
- Gekirin (逆鱗 Gekirin?, literally meaning "Imperial Wrath/Inverted Scale"): After using Pasta Machine, Kaku uses his Four Sword Style technique, by using his elongated arms and legs to fire powerful multiple slashes at the opponent. It, again, has an emphasis on the suffix kirin. In the FUNimation dub and Viz Manga, this is called Fury Slash.
- Rankyaku "Neji Hakujin" (嵐脚「ネジ白刃」 Rankyaku "Neji Hakujin"?, literally meaning "Storm Leg: 'Screwing White Blade'"): Used in half-giraffe form. He does a normal Rankyaku after using his Kyoku Bigan Kirimanjaro, then twists his neck into a screw so the Rankyaku spins in a drill motion. In the Viz Manga, this is called Tempest Kick Spinning White Blade.
- Rankyaku "Rodan" (嵐脚「龍断」 Rankyaku "Rōdan"?, literally meaning "Storm Leg: 'Dragon Sever'"): Used in half-giraffe form. Kaku uses an upward Rankyaku with both of his back legs, creating a large cut similar in appearance to a dragon's fang. In the Viz Manga, this is called Tempest Kick Dragon Cut.
- Rankyaku "Shuriken" (嵐脚「手裏剣」 Rankyaku "Shuriken"?, literally meaning "Storm Leg: 'Shuriken'"): Kaku fires multiple Rankyaku blades in the shape of shuriken. In One Piece: Unlimited Adventure (dubbed by FUNimation), this is called Rankyaku: Shuriken, and in the FUNimation dub and Viz Manga, this is called Tempest Kick Shuriken.
- Shortly after Nefertari Vivi leaves the Straw Hat Pirates, the crew-members were very sad; when Zoro suggests they should have kept Vivi by force, each Straw Hat jeers at him. Monkey D. Luffy's jeer was "Santoryu", but then changed it to "Yontoryu" when Usopp mentioned that "Santoryu" wasn't an insult.