Can I get a small recap on a few things? (Solved)

1. Ike wants spirits to go into reverse form in order to extract the crystals so he can absorb that power and awaken power of their Demon kings.

2. Eliot wants to save the world without having to kill spirits.

3. Rasiel is changed into Demon king whose power is to create those monsters and Nibelcole, a demispirit.

You will see in episode 5. Do you remember in season 3 when Ellen sent a message for Eliot? When she had battle against Fraxinus, she said: "Eliot, damn Eliot. You traitor etc." Meaning they worked together before. Also Eliot made organisation Ratatosk.

They'll most likely go into details a bit more the next episode.. but if you don't mind waiting until then:

Ike, Eliott and Ellen were among the last actual magic users in the world, they grew up in a small village. Humans came and destroyed their village. They swore revenge.

30 years ago they created a device that let them gather all the mana in the area, and thus Mio was created, also this event blew up part of the Asian continent. Ike and an easy impressionable Ellen decide to use Mio's powers to get revenge on mankind. Eliott understands that is wrong and it would make them just as evil as the ones who destroyed their village so he creates Ratatoskr to save the Spirits. Karen is Ellen's sister and she decides to follow Eliott because she wants the D.

The girl with manipulated memory is Artemisia Ashcroft, she had some unique brainwaves they used for creating those Bandersnatch drone things. DEM used her, simple as that.

The LN has more details about the whole thing, but not by much.. a lot of character are simply added, for convenience

Number 4 I believe ur talking about the ast team ryouko. She and the astray were initially the antagonists before dem took over in season 2. Their memories weren't manipulated but timeline shift in season 3 made the ast forget that origami joined dem, and tohka being a spirit I believe.

@SpiderMiles3523 No no, the blond haired girl, her memory was unlocked in episode 3, and the characters kept saying she was brain washed or had her memories altered.

@APolygons2 Basically,origami and Mana said that she got brain washed because she used to hate what Dem is doing.She used to be apart of the British equivalent of AST which is the SSS.