The Marines do not have a system of rank insignia per se. There is significant variation in the kind of uniform worn by officers, with many options to wear a variety of dress showcasing their own eccentric style. Marines are also allowed to wield whatever weapon they are most comfortable with, no matter how unusual it is. They are even free to fight bare-handed. However, as a general rule set down by the author, uniform guidelines are as follows:
- Upon first entering the Marines, new recruits are given the standard uniform, consisting of a white, short-sleeved shirt emblazoned with the Marine emblem; a simplified seagull with the word "MARINE" underneath it, on the back; a blue neckerchief; dark blue trousers; and a baseball cap also with the word "MARINE" across the front. All officers at the rank of seaman (一等兵 Ittōhei?) and below wear this. The quasi-rank of "Zatsuyō" (雑用 Zatsuyō?) adds the kanji 雑 Zatsu ("various" or "odds and ends") to the sleeves, and to the Marine emblem on the back.
- Once an officer has reached the rank of petty officer (伍長 Gochō?), he or she can choose from a number of different uniforms, including his or her personal clothes. Only those who really want to appear "sailor-like" will stay with a more traditional uniform.
- Sailors at the rank of ensign (少尉 Shōi?) and above are allowed to wear the coat with "Justice" (正義Seigi?) on the back. This coat tends to be worn like a cape, draped over the shoulders with the arms not in the sleeves. It should be noted that the sleeves of these coats are often much longer than the wearers' arms.
- For the rank of lieutenant commander (少佐 Shōsa?) and above, a suit worn underneath the "Justice" coat is the preferred attire.
There are, of course, exceptions: Jango and Fullbody wear their own clothes with the "MARINE" hat, despite holding the rank of "seaman recruit" (三等兵 Santōhei?). This may have something to do with the exceptional circumstances by which both of these men were brought into their present situation, or it may simply be lenience on the part of their Rear-admiral, Hina.