Japanese Armor Types Illustrated c. 1868 via The New York Public Library
These are wonderful! Lets go through them shall we?
The first image in the top left appears to be a fairly straightforward retainer, wearing the jinbaori surcoat, no chest armor of any kind, kote (the armor around the forearms) and kusazuri which is the skirt armor.
Below that appears to be some manner of naginata wielding soldier, he wears an eboshi (that black hat), he is likely not a noble as generally theirs were starched to stand up straight. He likely wears the simple Haramaki style armor, wherein the ‘Do’ or breastplates are connected to the skirting.
Below him is your basic Ashigaru harquebusier, Ashigaru being the core of the medieval Japanese army, composed of low ranking soldiers outfitted with pikes, flintlocks and bows and arrows, they were the predominant group on the field. He wears a cheap and simple to produce set of armor, the yokohagi-do with accompanying suso-ita, basically a breastplate and skirt to protect the upper legs. His hat is a simple jingasa.
The large fellow in the center likely depicts an early samurai (12th century or thereabouts), wearing oyoroi style armor. The armor is made from interlocking pieces of lacquered wood, later these pieces would be replaced with metal. It was boxy, and stiff. His helmet is another way to place him as 12th century commander as the kuwagata are quite large, that being the wings sprouting from the front of the helmet.
Below that we have a noble archer, potentially a more classical version of the samurai, from Japans earlier history where combat was often decided through individual duels. He has a peculiar style of sheath for his sword, which was likely covered in hair, giving it that bushy look.
Beside him to the right in the green and purple is what I believe to be the court dress of an Ashikaga shogun, the Ashikaga being the ruling shogunate for many years before collapsing into ruin. This could also potentially be the regular dress for any shogun, up to and including the Tokugawa shogunate of the 17-19th centuries.
I believe the noble samurai in the top right is wearing a haramaki style armor, which became popular after the oyoroi, and was commonly used up to the 15th century.
The last two are somewhat harder to place, likely representing the changes between the 15th and 16th century styles of armor, where the helmets became more ornate in some areas, but less wide, and the armor grew more and more flexible.
