Mogu Mogu no Mi

The Mogu Mogu no Mi, also known as the Mogu Mogu Fruit, is a Zoan type Devil Fruit that gives it's user the power to become a mole. Mogu is short for "mogura," the Japanese word for mole. It can also be short for "mogumogu," a phrase meaning to chew one's words, which describes Miss Merry Christmas' manner of speech. In the Viz Manga and 4Kids dub, it is called the Diggy-Diggy Fruit. It was eaten by Miss Merry Christmas. It's powers were first explained by Chopper to Usopp before actually being clearly seen.

Strengths and Weaknesses
The major strength of the fruit, as demonstrated by Miss Merry Christmas, is that the user is able to move underground as if they were swimming in a pool. They are also able to attack their enemies with mole-claws the size of bananas. A powerful enough user will just simply smash through any stone structures in their way without losing any speed whilst traveling underground.

The tunnels that the user makes by digging can also be used by their allies to aid them in fighting. Unfortunately, the tunnels can also be used by enemies as well. The major weakness of this is that all the tunnels that are dug are interconnected; this means a large scale attack, like an explosion, sent into the tunnels could greatly damage the user and their allies.

It is currently unknown if the user's powers would be greatly impaired if they were placed in an area where digging would be difficult. Other than that the user is also affected by the same main weaknesses as other Devil Fruit users.

Usage
The fruit's bestowed powers, as used by Miss Merry Christmas, have been used primarily for combat. During her and Mr. 4's battle against Usopp and Chopper, the way she used her mole hybrid form in a sequence of events, greatly resembled to the game of "whack a mole". Mainly when Usopp tried to use the 5-Ton Hammer on her and she kept retreating into her holes. The majority of her named techniques while in her mole hybrid form were also first seen being used during the same battle. The named techniques that are used by Miss Merry Christmas that involve the Devil Fruit are as follows:


 * Mogura Tonpō: Mogugyo (土竜遁法 土竜魚) Mole Digging Technique: Mole-Fish: From the opening of one of her molehills, Miss Merry Christmas leaps into the air and swan dives underground. This technique is called Mole Swimming Stealth Style in the Viz Manga and Woodchuck Swimming Stealth Style in the 4Kids dub.
 * Mogura Banana (土竜 平手撃ち) Mole Banana: Miss Merry Christmas attacks her opponent with her half-mole form's claws. This attack can be done from underground while close to the surface or by leaping out at her opponent. It's name is derived from when she attacks her opponent. The way she attacks, as well as her claws, resembles a banana. In the 4Kids dub, this is called Woodchuck Banana.
 * Mogurazuka Highway (モグラ塚ハイウェイ) Molehill Highway: Miss Merry Christmas grabs her opponent's feet from underground and starts tunneling rapidly, dragging him/her along the surface with her. This is called Moletown Highway in the Viz Manga and FUNimation dub and Woodchuck Highway: Off and Running in the 4Kids dub.
 * Mogu Mogu Impact (モグモグ玉砕): After performing Mogurazuka Highway, Miss Merry Christmas steers her opponent into a wall, smashing him/her into it with great force. This is called Mole Impact in the Viz Manga and Woodchuck Wallbanger in the 4Kids dub.

Translation and Dub Issues
In the 4Kids dub, in order to match with the Miss Merry Christmas' name change to Miss Groundhog's Day, the animal with which the fruit allows her turn to was also changed. The animal which she turns to was changed from a mole to a groundhog. This change also included changing Usopp's penguin assumption regarding Miss Merry Christmas' hybrid form. This change however was only dialouge-wise. Despite the dub stating she was a groundhog, she still looked like a mole.

Trivia

 * A running gag due to the Miss Merry Christmas' shape when she turns to a mole hybrid is that Usopp mistakes her for a penguin.