- "Mochi" is the name of a sweet rice cake, and can also be a descriptor for sticky things in general.
Strengths and Weaknesses
The user is given the ability to control large amounts of mochi; the mochi is thick enough to be used as a large blunt weapon, and is capable of trapping people, even extremely strong ones, due to its stickiness, especially if empowered by Busoshoku Haki. Its thickness and viscosity is such that large-caliber gunfire is completely unable to pierce through it. Due to its malleability, the user is capable of shaping the mochi into a massive variety of shapes, such as fists, tendrils, and even spiked clubs.
As a "special" Paramecia, the user can actually change their body into mochi, akin to a Logia. When combined with mastery over Kenbunshoku Haki, the user can predict the future and manipulate the shape of their bodies accordingly to avoid being hit by attacks, unless the user loses their calm, which nullifies their ability to predict.
However, the mochi loses much of its stickiness if a sufficient amount of liquid is applied to it, allowing a trapped opponent to free themselves from it; this was first seen when Jinbe used Fishman Karate to douse Katakuri's leg with black tea, freeing the trapped Luffy. The mochi is edible, especially if the user is not actively controlling it. Otherwise, the user is affected by the standard Devil Fruit weaknesses.
Katakuri uses his fruit in combat, and is capable of controlling large amounts of mochi with high precision. He has been shown extending his limb using mochi for various tasks. He extended his leg to form an extremely fast, large, tentacle-like blunt weapon, with much of it imbued with Haki to harm the rubber-bodied Monkey D. Luffy, and at the same time, entrapping him. He also used it to extend his hand to rescue Charlotte Brûlée from her captives, and secure Charlotte Galette while the Big Mom Pirates fell from Whole Cake Chateau.
He also used his devil fruit to create mochi earplugs in order to stand to his mother's scream after the picture of Mother Carmel was broken during the Tea Party. He also distributed these earplugs to his siblings as well. He also used his mochi to plug up the cannons of Capone Bege's Big Father, causing them to explode when fired.
This Devil Fruit is similar to the Gomu Gomu no Mi, as it gives the user's body the properties of a "stretchy" substance that allows them to extend their limbs and expand their bodies at will. This similarity was noted by Carrot and Katakuri himself. However, unlike the rubber powers gained from the Gomu Gomu no Mi, the user can also fully transform their body into their substance (in this case, mochi) and even produce it outside of their body and manipulate it. This allows Katakuri to imitate a few of Luffy's own techniques such as Gomu Gomu no Hawk Gatling and Gomu Gomu no Elephant Gun, with his ability to manipulate mochi making him further capable of adding twists of his own such as extra mochi arms for his version of Gomu Gomu no Hawk Gatling. Due to Katakuri's physical abilities, those replicated techniques end up being more effective than Luffy's attacks.
Because of Katakuri's highly advanced Kenbunshoku Haki, he is able to change the shape of his mochi body to dodge attacks, causing Haki-imbued punches to pass through air rather than hit him. He was able to transform into mochi to block off bullets and reform after his body was bisected. However, he must remain calm to use his Kenbunshoku Haki effectively to predict where the opponent will strike and shift his body accordingly, or else he is susceptible to Haki like any Devil Fruit user.
As an awakened Devil Fruit user, Katakuri can turn surrounding inorganic material into mochi, spreading the adhesive substance around to enhance his range of attacks and capturing his opponents.
- Yanagi Mochi (柳モチ Yanagi Mochi?, literally meaning "Willow Mochi"): Katakuri sprouts multiple long tendrils of mochi mimicking his leg and uses them to stomp down on his opponent. This was first used against Luffy, but was only named the second time it was used. This is called Willow Mochi in the Viz Manga.
- Mochi Tsuki (モチ突 (ツキ) Mochi Tsuki?, literally meaning "Mochi Thrust"): Katakuri, while holding his spear Mogura, tightly twists his mochi arm and then untwists it while thrusting the spear forward, creating a powerful drilling stab that can easily pierce through and destroy buildings and structures. It was first used against Luffy, who barely managed to dodge it, causing the attack to instead hit a building and completely destroy it. It was later used against Luffy successfully, and created a massive, gaping wound on the side of his torso.  This is called Mochi Thrust in the Viz Manga. The name of this technique is pun with mochitsuki (餅搗き?), a traditional ceremony to make mochi.
- Kaku Mochi (角 (かく) モチ Kaku Mochi?, literally meaning "Square Mochi"): Katakuri turns his arms and hands into mochi and then compresses them until they acquire a square-like shape. He then hardens them with Busoshoku Haki and punches his opponent. The compact, tight square-shape of the fists result in attacks that are a lot stronger than a regular Haki-enhanced punch, enough to make Luffy feel great pain when clashing fists with him. It was first used against two chefs. This is called Edged Mochi in the Viz Manga. The name of the technique references a way to prepare mochi in Japan in the form of hard, square-shaped blocks, instead of the gelatinous consistency of usual mochi.
- Yaki Mochi (焼餅 (ヤキモチ) Yaki Mochi?, literally meaning "Grilled Mochi"): Katakuri inflates his mochi forearm until the pressure causes it to explode, propelling his Haki-embedded fist at his target from a distance. The speed of the fist is so high that it catches on fire due to friction. It was first used against Monkey D. Luffy during their fight in the Mirro-World. Yakimochi is a form of grilled mochi. This is called Burning Mochi in the Viz Manga.
- Zan Giri Mochi (斬・切・餅 (ザン・ギリ・モチ) Zan Giri Mochi?, literally meaning "Sliced Mochi): Katakuri turns his entire body into mochi and rapidly spins towards his opponent in a donut-like shape. When he reaches his opponent he returns to normal shape and, using the momentum from the spinning, slams his enlarged mochi forearm, covered in spikes and hardened with Busoshoku Haki, into his opponent with tremendous force. Aside from the damage caused by the powerful impact, his opponent will also be stuck to his forearm due to the stickiness of the mochi, which Katakuri then uses to swing his arm through the air before smashing it down into the ground, crushing his opponent under its weight with enough force to create a large crater. It was first used against Luffy during their fight in Mirro-World. This is called Buzz Cut Mochi in the Viz Manga.
- Nagare Mochi (流れモチ Nagare Mochi?, literally meaning "Flowing Mochi"): Using his awakened powers, Katakuri transforms the ground around him into mochi and uses it to capture his opponent from a far-away distance. It was first used to capture Luffy while he was running away. This is called Flowing Mochi in the Viz Manga.
- Kagami Mochi (加々身 (かがみ) モチ Kagami Mochi?, literally meaning "Concentrated Mochi"): Using his awakened powers, Katakuri transforms nearby walls and ceilings into mochi, and then causes them to collapse on his opponent, burying them under a large pile of mochi and causing them to suffocate. It was first used to try to eliminate Luffy. This is called Mirror Mochi in the Viz Manga. The name of this technique and its final form are a pun of kagami mochi (鏡餅?), a traditional Japanese New Year's decoration, as well as the fact that the technique was first used in the Mirro-World.
- Amadare Mochi (雨垂モチ Amadare Mochi?, literally meaning "Raindrop Mochi"): Using his awakened powers, Katakuri transforms nearby surfaces into mochi and shapes them into multiple blunt-ended tendrils. He then has them converge on his opponent with great force, attempting to crush them. This is called Rainfall Mochi in the Viz Manga.
- Muso Donuts (無双ドーナツ Musō Dōnatsu?, literally meaning "Peerless Donuts"): Using his awakened powers, Katakuri summons tendrils of mochi from the ground and loops them into the shape of donuts. The name of this technique is a reflection of Katakuri's love for donuts. It was first used against Monkey D. Luffy. This is called Unstoppable Donuts in the Viz Manga.
- Chikara Mochi (力餅 Chikara Mochi?, literally meaning "Power Mochi"): Katakuri shapes the donut-shaped pieces of mochi into giant arms, which are square shaped similar to his Kaku Mochi technique, and hardens them with Busoshoku Haki. With a layer of mochi over his hands, he then manipulates the mochi arms to punch his opponent with extreme force, enough to harm and send Luffy flying while he was in his highly resilient Gear Fourth mode. This is called Power Mochi in the Viz Manga. The name of this technique is a pun with chikaramochi (力持ち?), which means "strong man".
- Mochi Ginchaku (餅吟着 (モチギンチャク) Mochi Ginchaku?, literally meaning "Mochi Singing Result"): A more powerful version of Chikara Mochi, Katakuri summons multiple mochi donuts around his opponent, shapes them into Busoshoku Haki-enhanced arms, and then has them strike at his opponent from various directions repeatedly, pummeling his target into the ground. It was first used against Luffy. This is called Mochi Anemone in the Viz Manga. The name of this technique is a pun on mochi-kinchaku or mochi-ginchaku, a bag-shaped type of mochi.
- This Devil Fruit was initially introduced as a Logia in the Magazine release, but was changed into a Paramecia in the Volume version, though is stated to be a "special Paramecia" (特殊な超人系 tokushuna Paramishia?).
- The unnamed Devil Fruit eaten by Tama also allows her to produce mochi from her body. Tama can only produce small dango-sized mochi from her cheek, making her fruit much weaker in direct combat. However, it has the additional effect of making animals who eat the mochi tame and friendly to her.