I received a request to list all the organizations in the world and their relationship with each other. I believe that this is a reasonable request since they are a lot of groups mentioned throughout the story.
So I'll take this time to name them and give non-spoiler descriptions.
New Era- A mysterious organization with unknown origins and questionable objectives. The organization is made up of several smaller organizations that possesses unimaginable strength and influence. It is rumored to possess enough strength to rampage through the Heaven and hells. Its hierarchy system is unknown as well if it has a single leader. It has shown to be involved with some Higher Beings like Enlil.
Genesis- A mysterious organization that specializes in biological engineering. It is apart of New Era and is headed by an individual known only as Noah. It has been hinted that Genesis proud beings similar to Kaido called Children Of Genesis
Nexus- A group of incredibly strong fighters who act as the main combat force of the New Era. It is headed by Ringo/Klick and has the Strongest Dragon Proxy Killo as one of its members.
MYTH- a miilitary organization that uses Alchemy to create futuristic technology and weapons. It's the world's biggest supplier of weapons and is also apart of New Era. It is headed by Hephaestus proxy Demon Blacksmith Miguel, who was the Millennium Genius prior to Alec.
Hell Dynasty- A group made up entirely of Tyrants, which is also apart of New Era. The only known members are Arsene Mors and the late Kill Point who died during the Primus Rebellion War.
Apostasia- Another branch of New era. Nothing is known about them as of yet.
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Juggernauts- Nicknamed the Trumps, it's a legendary mercenary group formed by Rihan and Loki's proxy Warmonger Julian 1000 years ago. The identity of the members are unknown to anyone outside of the group. However, because each member is a monster it's speculated that its members are all world renowned warriors hiding their identities. The group is so notorious that they're wanted in every empire and most countries in the world. They've committed every crime known to man and is so feared that just posing as a member is enough for you make a country tremble. However, doing that is like signing your own death certificate since you suffer a miserable death at the hands of the real members.
Mors Clan- a clan of assassins headed by Kimiko. They are undoubtedly the #1 group of assassins in history.
Pandora- A powerful military organization founded by Hercules Proxy, Fighting God Rood and Nova's wife Neo. It is one of the top five armies on the Hero side, and is feared worldwide. The army is massive and very powerful.
Camelot- a military organization/ country headed by Arthur Pendragon's proxy, Perfect Queen Maya. Other than Maya it has several powerful proxies who are apart of her round table council. It has one of the five strongest army on the hero side.
Olympias- Founded by Alexander the Great proxy, Conquering King Guzan. It is arguably the biggest army in the world and one of the most powerful.
Seven Swords Of Lucifer- Seven swordsmen who serves Lucifer's Proxy, History Strongest Demon Proxy, Nine Hells Dante. More about them in the next couple chapters.
Asgard Empire- The oldest and most powerful empire in the world. It is made up of almost every Norse proxy with Odin's Proxy War Sage Stein leading them. It is unrivaled and considered eternal.
Morningstar Empire- Created by nine hells Dante, it is the largest Demon empire in history. More on it in this arc.
Zebul Empire- An empire created by Beelzebub proxy, Demon Sovereign Zara, which is 2nd only to Dante on the demon side.
Black Scriptures Of Beelzebub- Zara's personal warriors and apostles. They are all powerful and merciless. They're one of the reasons the Zebul Empire grew so strong so fast.
There are others like the Sanskrit Federation and the Undead Country but I'm too tired to explain anymore.
hope this helps to refresh your memory.