Tall and blonde, RPK has shoulder length hair with the ears and long tail of a Siberian Tiger. Owing to her more feline traits, she also has cat like eyes that are a deep crimson in colour.
Thanks to RPK's thicker receiver she is also "well endowed" when it comes to bust size, leading her to pick on some others that are more slender like vz. 58.
RPK is fiercely loyal to Akaganekou students and the school itself saying to Modern-lit "But I am not giving you any information about my allies". She acts as an older sister to the other Red Steel girls, looking out for the other girls like M70B1 and Saiga. RPK has even gone as far as making Saiga and Bizon count to 100 while in the bath to make sure they get clean.
While she faces Seishou students in battle constantly, she is not above recognizing and helping those that have helped her. Dressing up as a maid and giving Gengoku information on Red Steel as "a service" for bandaging and taking care of her and M70B1.
All in all, RPK maybe be a die hard Red Steel girl but understands to treat people well that have treated her well and to take care of the other girls in Red Steel.
In Real Life
With the development of the AK-47 and RPD by the Soviet Union in the mid-40's, they aimed to simplify their manufacturing process and logistics for not only their own army but the armies of the Warsaw Pact as well.
After a great deal of time and research, the Soviets achieved this with the introduction of the AKM in 1959. Ticking the boxes of simpler design, easier manufacturing, and lighter weight the Soviets now had a weapon to arm their massive armies and those of their allies but needed a squad light machine gun to go with it. While the RPD was a capable light machine gun, it created an extra strain on logistics for the Soviets as it had no parts commonality with the AKM and was belt fed from drums, meaning that even the magazines were different. These issues were solved with the reveal of the RPK in 1961 as the new squad light machine gun. The RPK had large parts commonality with the AKM and used the same style magazines, greatly simplifying logistics for the Soviets.
After it's introduction of the RPK it was exported to various markets in Eastern Europe, Africa, Asia, and South/Central America. It enjoyed great success in these markets as a cheap but reliable light machine gun to be attached to infantry squads.
Over the years the RPK has been seen in many wars such as Vietnam, Salvadorian and Lebanese civil wars, Soviet-Sino border clashes, Soviet-Afghan war, and the South African Border wars to name a few.
While seeing such ubiquitous service, the traditional RPK chambered in 7.62x39 is no longer the main light machine gun of the Russian Federation as it's successor , the RPK-74/74M, has taken over as the main front line light machine gun. In other countries however, the RPK still is their main LMG and will be for the foreseeable future.
In the realm of squad support fire, the RPK is a durable and reliable contender. With many similarities of an AKM, the action is simple and hard to jam in all adverse conditions and while not soldier proof, the RPK is very soldier resistant. If a problem where ever to crop up with the RPK it's parts commonality with the AKM means that repairing it would be simple for soldiers.
As a light machine gun, the RPK fits a good role with a potent round but has several issues that hinder its performance in that role. Unlike its receiver, which was thickened to compensate for the RPK's position as an LMG, the fact that it is closed bolt and does not have a quick change barrel mean that it's effective rate of fire is limited. Whereas something like the M60 has a quick change barrel to prevent overheating of the barrel and allow for consistent and sustained suppressive fire, the RPK is susceptible to barrel damage and rounds cooking off due to excess heat if fired continuously for long periods.
Albania [as the ASh-78 Tip-2]
Central African Republic
East Germany [Formerly]
Iran [as the BB-Kalash]
Iraq [as the "Al Quds"]
North Korea [as the Type 64]
Poland [in limited numbers]
Romania [as the PA md. 64]
Russia [Formerly, replaced with RPK-74/74M]
If you don't mind picking up a variant build, a Romanian AES-10B imported buy Century can be had for little more than one thousand USD. There is also the Arsenal SA RPK-7 that will run you about 2500 USD on the second hand market. James River Armory has been building RPKs from Yugoslavian parts kits and labels them the M72B1, and they can be had for under 1000 USD at time of writing. A true Russian RPK from a parts kit will run you about 2000 USD if you pick one up from Legion, this however will have some US parts in order to comply with 922r regulations.
Sadly, for the great white north, the RPK and any variant there of is considered a prohibited firearm and can't be owned without a special license.
One can be owned in Switzerland as well, but at the time of writing an average price for one could not be found.