Mr. 4 has a four on his bat and shirt. He's a large, and inhumanly strong batter. He wields a four ton bat. Being very dimwitted, he only listens to his partner's, Miss Merry Christmas, orders and rarely speaks. He has a dog named Lasso, who was once a gun who "ate" the Inu Inu no Mi (Mutt Mutt Fruit, in the English dubs), who now shoots explosive baseballs for Mr. 4 to hit at his opponents.