Babe

Mr. 4 is partner of Miss Merry Christmas.

Appearance
Mr. 4 is rather tall and fat, wearing a green shirt that covers most of his body with black pants and gray running shoes. Like all other officer agents, his number is expressed somewhere on his clothing or his person. Mr. 4 has an obscure "4" design on his shirt, as well as a "4" on his baseball bat.

Strangely, even though he is drawn with blond hair on the cover of volume 21 and in the anime, the manga itself depicts his hair color as black. This is not the first time though Oda has depicted a blond haired character this way; Yasopp is also shown with black hair in the manga even though he has blond hair.

Personality
Mr.4 was the slow and dimwitted partner of Miss Merry Christmas. He seems incapable of thinking for himself at all and often just does as his partner tells him to do. He laughs freely, but speaks rarely- in contrast to his partner, he speaks very slowly, usually taking most of a scene to articulate a short sentence.

Abilities and Powers
He is one of two officer agents without a Devil Fruit ability, the other being Miss Goldenweek. He is very strong, but extremely slow in nature, so without Miss Merry Christmas handling the "intelligence", he would not succeed. He and his partner are actually, in terms of physical power, stronger than the Mr. 3 Team, but are a lower rank because Mr. 3 is much smarter.

He has a dog called Lasso, which was originally a gun, but "ate" (or rather, merged with) the Inu Inu no Mi, Model Dachshund, a Devil Fruit (イヌイヌの実 モデル ダックスフンド Inu Inu no Mi Moderu Dakkusufundo, called the "Mutt Mutt Fruit in the English anime) and became a gun-dog, who shoots exploding baseballs whenever he sneezes. Mr. 4 then takes out his 4 ton baseball bat and hits the balls at his enemies.

Techniques:

Yonhyabban Punk Knock (400 Punk Knock): This attack's not officially named by him, but by his partner Miss Merry Christmas. He has Lasso shoot a huge group of his exploding baseballs then Mr. 4 hits half of them back at a surprisingly swift speed into the cluster detonating them all at once and creating a massive explosion.

Mogurazuka Yonban Kousaten (Molehill Intersection Number 4)/Moletown Cleanup Hitter: A combo attack with Miss Merry Christmas, first Miss Merry Christmas uses her Mogurazuka Highway technique and carries the opponent past Mr. 4 who, upon hearing her call out the attack, smacks the captive with his 4-ton bat causing massive damage to anyone unlucky enough to be the victim of this attack, though he may accidentally hit an ally as he is too dim witted to note differences in the voice.

History
He, Lasso, and Miss Merry Christmas take on Usopp and Tony Tony Chopper during the Straw Hat Pirates' final fights with the Baroque Works during the Arabasta arc, and he manages to severely injure Usopp using a combined attack with Miss Merry Christmas. But Usopp tricks him into knocking out his partner, and then, then using Chopper's horns as a slingshot, defeats Mr. 4 by shooting an extremely fast hammer at him (the move called Hitsatsu UsoCho Hammer Suisei or UsoCho Hammer Comet) and knocking him (and Lasso) into a stone structure. Afterward both Mr. 4 and Merry Christmas appear to be Killed by one of Lasso's exploding baseballs. However, all three later seen alive, but in prison, in Miss Goldenweek's chapter title page story. They manage to escape and are now working in the new Spiders Cafe. He is now the only male officer agent other then Mr. 5 to be working at the Spiders cafe

Trivia

 * Miss Goldenweek's Rainbow Color Trap reveals that his dream was to become a pizza delivery boy ("Pizza within 30 hours" as his apron says).
 * The Mr. 4 pair's theme is baseball. It is a reference to a baseball strategy where you have your best hitter as the 4th batter in the batting line-up. If the first 3 batters manage to get a base each, the 4th player then has a chance to get the best points for the team.