Yamatai Imperial Navy Marines

Imperial Navy Marines are members of the Yamatai Imperial Navy stationed aboard starships as a light infantry force, primarily as security personnel, military police and troops to be used in case of boarding activities. The Marines are considered a part of the crew of a ship, even if they do not participate in the direct operation of the vessel, and do not have a formal command structure beyond their assigned vessels with the highest rank being Captain and their commanding officer being whoever is commanding the ship they are on.

Recruitment, training and organisation
The Navy Marines often recruits failed fighter pilots or officer cadets who are still determined to be in the Imperial Navy. It is also open to transfers from other branches of the Navy, and rarely rejects candidates. Civilian recruitment also occurs, and the Navy Marines are commonly seen as an "easier" Navy vocation for civilians intending to join the Navy but with few educational qualifications or intent to learn high-level skills. As a result, morale amongst Marines is often low.

Training takes place on the Imperial Navy's Shikishima-17 space platform around Niigata. Cadets learn basic infantry tactics, close-quarters combat, shipboard combat and security procedures over a two month course. Navy Marine officers are selected for their leadership capabilities and attend an additional two week course. An optional martial arts program is also available for Navy Marines. Following numerous cases of negligence by Navy Marine instructors, the SNLF has taken over training of the Marines.

Like the SNLF, the Marines rank system follows that of the Imperial Army, with the lowest rank being Private and the highest rank only being Captain as Marine units are rarely larger than company strength. Navy Marine captains are able to transfer to the SNLF as a 2nd Lieutenant.

Uniforms and equipment
The Marines are primarily equipped for close-range, shipboard combat as well as security functions. They use the same kabuto-inspired helmet as some Imperial Army security forces and typically wear a standard plate-carrier. Like the rest of the Imperial Navy, Marines' uniforms are black, with a red armband for officers. There is no dress uniform.

For the close-quarters combat the Marines are intended for, they are equipped with the O-08 automatic shotgun, the O-40 shotgun and the Nu-99 submachine gun. Their standard sidearm is the Yo-79 pistol.

Relationship with other units
The relationship between Marines and pilots is particularly low due to the methods in which the Marines recruit members.

The Imperial Navy Marines are not to be confused with the SNLF, which is the dedicated marine force of the Imperial Navy, tasked with planetary assaults as well as on-ship security and boarding actions. In the case of such events, it is known that ship captains often prefer to deploy the SNLF rather than their own Marines, creating intense rivalry between the two vastly different but similar units.

Another force with a similar name is the Imperial Army Marines, who specialise in terrestrial amphibious attacks.