Luffy seems to have an unstoppable appetite, a characteristic that is common to the Japanese archetype of the (at times simple-minded) young male hero/adventurer with a heart of gold; perhaps the hunger more so in Luffy's case due to having an elastic stomach. Luffy is also another one of the several characters given the middle initial "D." Although Luffy is fairly lightheaded and a funny character, he has an unstoppable sense of determination, optimism, and commitment and will do anything to stand up for his friends and comrades. Along with that, he has great courage to back it up as well as unbelievable strength. Ever since consuming the devil fruit he was shown to be not worried about his inability to swim, much like his brother. Much of these traits are common among D's. His only display of true fear is towards his grandfather, to the point that he is intimidated at the mere mention of him. Luffy never kills any of his enemies, no matter how cold-hearted they are; instead, he frequently sends the villain flying, knocking them out or beating them to a point that they are almost near death, which results in some of the villains searching for revenge, such as Buggy the Clown and Alvida. Oda explains that it's not a question of morality so much as a matter of punishing the villains for their crimes - he feels that killing the villains lets them off too lightly, whereas he considers letting them live to see their dreams be ruined a far more fitting punishment. Luffy's dream is to find the One Piece and become Pirate King. He knows that to achieve his goal, he will have to defeat many strong opponents, including the World Government and his childhood hero Shanks.

Levi is known as humanity's most powerful soldier. He's ranked as Captain of the Scouting Legion division. Levi is also the leader of the Special Operations Squad, an elite team that he hand-picked in order to protect Eren Yeager. While it is said that he is blunt and unapproachable, it is noted that he has a strong respect for structure and discipline. There are rumors that he was originally part of underground crime before he became a soldier. Although he often appears to be unfriendly, he cares deeply for his team and has never undervalued human life. He is also a notorious clean-freak.