@xmyst
Argon - The holy empire and the location that the story is currently taking place.
Kruma/Kroma - this is the country that went into Argon to slay the green dragon and smuggle it's remains out of the country without paying the 80% tax that Argon levies (basically they are stealing a dragon).
Corrint - The strongest country currently with the most military power. They are attempting to steal the smuggled green dragon remains so they can also avoid Argons taxes.
Krataus - The country that Dark is currently associated it (the one with the wizard that turned him into a girl). They aren't a part of this current exchange, but since Dark is a representative of that country you can consider them involved in that manner.
Trovia - a country that was defeated by Krataus. Their prince has currently pledged loyalty tom Krataus until he becomes stronger to get revenge. They are not involved in the current story arch (chapter 50)
Major character plot points:
Darks territory in Kratus, Chirea chased an Orc army into neighboring Argon (chapter 79 and 80) in order to have an excuse to opening up negotiations which were handled by Dark's proxy, Count Kisley. As a result Argon is paving a Raod into Chirea territory. Because of this Dark was curious as to how strong Argon actually is in military strength which is why he's observing this mess of a battle (see chapter 91 and 92).
Minerva is one of the stronger masters / grandmasters and is affiliated with Kruma/Kroma, but we don't know much about her.
Fassir / Pasire is a person from the fallen kingdom of Londbar which was destroyed by Kruma and was recently added to Dark's band of merry men (see chapters 87 -89 also 92 for when he was official recruited)
Fire Hammer is a dwarf who has skill in crafting weapons out of dragon bone. He also made the anti dragon weapons used to kill the green dragon that everyone is fighting over.
Mikael Doer/Douler is a major land owner in Argon who was assisting Kruma in obtaining the Dragon bones (see chapter 82, 91, and this chapter)
Marquis Taron Smer the guy who actually did the dragon slaying (chapter 84, 85 and 88). He used the Mercenaries, Fassir and Joe Nerman (dead) along with Dark's group as decoy's to make the young dragon waste it's breath early to give him the chance to overwhelm it. He's just a graduate from Kruma, not a master, but his titan is top notch so he's currently fighting with a Master from Corrint. Also if you re-read chapter 92 you'll see that he was also suspicious of Priestess Betty.
Duke Luen, also from Kruma, is one of the Masters of that country. (chapter 91-now) The second most powerful after Minerva whom you saw in this chapter.
Aroji and Legar are from the Holy Knight order who are currently observing the battle between Corrint and Kruma (see chapter 94)
Count Kamille Klodein is one of the masters from Corrint. Currently fighting the Graduate Marquis Taron. He wanted to kidnap Dark because he thought Dark was a spiritualist (chapter 54-55)
James is the red haired young master who is currently fighting Duke Luen. He's the one Dark scolded for calling him "young lady" and was upset that Kamille didn't get the same reaction when calling Dark a young lady.