Sounds like you have put a lot of thought and effort into it. Are you sure that you arnt being too ambitious, though? It sounds like it would take a couple of lifetimes to develop all that into a serie of novels. Which one are you writing first?
Baby dango
Ideally, I prefer starting with the occult first, due to their secretive nature as well as having the largest underground network spanning the entire planet. Makes it easier for world building, with different stories making references to the occult's existence to show that they are in the same universe. The esper city gets attacked by occult terrorists, the magical girls receive assistance due to the presumption that they are also part of the occult, wizard mercenaries hired to recover the otherworldly artifacts and etc. Some governments are controlled by the occult, which allows them to be aware of other organizations and having their hands in them.
Then my advice is to write a short story or two in that setting, and see where it takes you.
This post was originally in the World Building thread, but was ignored. Maybe I posted it in the wrong thread, so I'm reposting here.
I been trying to create a shared universe linking together several ideas for a few months. Eventually, everything will lead up to a Justice League style organization where all of them are revealed to public. Since I don't want there to be any plotholes that comes from overlapping universes, I'm posting this to receive some advice and find possible plotholes. The world itself is basically our world with minor changes.
Firstly, an artificial island was created in the middle of the Pacific ocean by the UN to facilitate the Esper program created by scientist Albert Nors Rhine. People who volunteered to undergo surgery and experimentation to receive special powers will then undergo observation to aid research. While initially received poorly by the public due to human experimentation, zero incidents and the large amount of benefits with ESP powers swayed people over. The volunteer's living expenses will be covered along with large amount of money. Abilities manifest randomly, so researchers prefer if entire families join the program to research on the effect of genetics on the abilities manifested. Albert N. Rhine also made several breakthrough in technology, creating technology that surpass modern technology so much that current engineers can't even begin to figure out. Since he pretty much keep all research to himself while also being a powerful esper, the UN decides to give him his own island that will stay politically neutral so that he will work for no single country. The island have its own police force to regulate the powerful espers with the advance technology, and the character given focus will be a member of the police. The story will focus on illegal experimentation by evil scientist, gangs formed by espers, class conflict by weaker and stronger espers, terrorists, corruption and spies sent by superpowers. The story will mostly be contained in the city until the time comes for the team-up. Rhine himself gained his knowledge by accident, when a wormhole sent him into a higher dimension beyond space-time containing the secrets of the universe. He couldn't process it all, so returned to Earth to make an individual that is capable of doing so, which is the basis for the creation of espers.
The second story focus on the occult. Ever since the middle ages, wizards have stayed in hiding to prevent persecution and revealing the secrets of the occult. They are divided into multiple sects and cabals who come into conflict with one another for dominance. Since magic is derived from a complicated system originating from superstition and myths, even the church have their own magicians, though their call their magic miracles that came from God. Some are affiliated with the government, some act as contract killers while others act as persecutors for criminals both magical and normal. The character of focus is an average guy who accidentally got thrown into a battle between two wizards, meaning he either joins a group as a wizard for protection or get killed to prevent the secret from being revealed. Demons and other magical creatures also exists to be exorcised or killed. Since they are hidden, nobody will know of them as well.
Next will be a Magical Girl plot. While both this and the former are considered magic, this magic comes from a different universe with a completely different system. The creatures came from a universe which is about to be destroyed by the Big Crunch. While originally they intended to move their entire planet into our universe, they discovered that our universe isn't suffering from the same fate, and instead expanding faster with each passing second. Said creatures figured that since the energy of our universe is increasing, they might as well tap into it to extend the lifespan of their universe while also preventing ours from getting destroyed in the Big Rip. However, they can't find a way to tap into the power source, so they decided to use their magical system to gain power from our universe. Every being have a finite amount of life energy when they are born, which decides how long they will live. Magic essentially shortens their lifespan, though you can also use magic by draining power from your surroundings. Anything created by magic should be permanent, but with slight tinkering, the creatures made it so that anything we create will dissipate and become energy to fill their universe. They also discover that, unlike them, the beings of our universe can refill themselves to their normal levels if given time. Our life energy still decreases with age, like all beings. Thus, the creatures introduced their magic system to the beings of our universe, but they started abusing them or rebelled against the creatures so that their creations stay permanent. Deciding not to reveal their secrets, creating a Masquerade to keep the magic users under control. They cook up lies to convince the people they chose to use magic, whether disguising themselves as a genie, a demon, or even as a god. The creature that chose the character of focus decided to use the Magical Girl genre as his guise, shape-shifting into a cute creature to convince the Japanese middle-school girl that she need to fight against Eldritch Abominations, which are really just aliens. Yes, Magical girls versus aliens is the premise. Over time, the character will discover other groups of magic users, with even more lies to link them together as well as eliminating those who found out. The real magicians will just think they are another magic cabal and help hide them.
Now, this one is the one that will link all of the stories together. An Eldritch Abomination called The Anomaly travels across the multiverse to collect weird magical objects to scatter across space-time, all for the sake of finding out what will happen. The Anomaly was also the one who created the wormhole that sucked in Rhine, the one who gave our universe a special device that provided unlimited energy, taught the magicians magic as well as caused all the weird things that seem to gather around our universe, especially Earth. The UN, discovering these objects, creates a secret organization themselves to collect them and keep them from falling in the wrong hands. The focus character travels around the world, across time and sometimes to multiple universes to collect the items as well as fighting those who seek to use their powers for selfish reasons. He is the one who finds the other secret organizations, and during a Crisis Crossover, unites all the focus characters under a banner to face a bigger threat.
I will add others later, so please help with these for now.