Of course we have the Red Roman Helmets and Other roman helmets but when have you actually seen a roman wear those?
Well time for a quick constructive post...
Those helmets are Roman, specifically from the Eastern Roman Empire, also known as the Byzantine Empire, (After the split, the Western Roman Empire fell after being saddled with all of the invasions/foreigners while lacking the rich resources of the ERE). The ERE remained a significant power due to the Queen of Cities with unmatched walls and wealth (Konstantinopolis or Constantinople now known as Istanbul) renown for controlling both of the two land paths required for Europe to trade with the east, (one of which the Queen of Cities literally stood on, as well as controlling the vast majority of all major sea routes.). The ERE lasted until the mid 15th century, falling mainly not due to military or economic fault but rather a long decline of political infighting which weakened the state via forced inaction (hence where the term "Byzantine Politics" arose.)
All of the current roman gear is from the ERE, and if you are not aware of the Eastern Roman Empire then I highly recommend that you look it up, for it is one of many critical cultures that has influenced most major historical events which have shaped the modern world, as well as being utterly fascinating.
As for the Japanese remarks, the armor used in-game resembles that commonly used even around the same era as the later part of the ERE, when gunpowder was starting to be a common sight on the battlefield.
I humbly suggest that the Original Poster brush up on some ancient history, and even Medieval and Renaissance era history (Primarily focusing on Europe and Asia), as you will learn a great many interesting things. An often overlooked bit from the western world is teachings about Eastern Europe, I suggest you start there.
Poll