2025/11/05: Searching through Japanese websites for anything I could find on Empire of Midnight, the best I've found so far was someone who wrote a summary on Okwave. The page is in Japanese, and linked below:
Okwave

The following is a translation of that person's summary:

"After Ororon’s death, Chiaki has completely changed. She cut her hair (giving her a boyish appearance), and without speaking or laughing, she is unable to recover from the pain of losing Ororon. She wanders the streets with a cigarette dangling from her lips, listless and expressionless. All of Chiaki's associates, including Shiro and Lucy, are dead. Rika is the only survivor, but she is in a coma.

Chiaki, who has become emotionally numb to killing, for example, by using her godly power to blow up the police station after being detained (killing some police officers), digs up Ororon's grave. She speaks to Ororon's remains, saying, "Now, I can finally be equal to you." Chiaki's wrists have several cuts from a razor, suggesting she has been repeatedly attempting suicide.

Othello finds and takes in this version of Chiaki. Chiaki and Othello enter into a physical relationship and start acting together, but Chiaki still doesn't speak, and when Othello holds her, she only cries and is consumed by sorrow.

In the demon world, Orga, not wanting Chiaki to be stolen by Heaven's forces, hires a professional assassin to try and kill Chiaki.

Ultimately, Othello decides, "If you stay with me, you’ll just get worse," and gives Chiaki up, leaving her with an acquaintance (a demon living in the human world).

However, Chiaki immediately runs away. She is targeted by low-level assassins on the street, but she doesn't resist and simply lets them have their way. (There is a monologue from Chiaki that says, "Hurry up and kill me," and "End this.")

In the end, a bystander (an older man) tries to help Chiaki and is about to be killed, which causes Chiaki to unleash her godly power once more, slaughtering all the assassins. Afterward, as Chiaki sits among a crowd, stained with blood, the professional assassin hired by Orga appears with a pistol. The assassin points the gun at Chiaki and is about to pull the trigger... and that is where it says "To Be Continued".

The serialization stopped right there. It ended at an extremely suspenseful point.

-Other Developments-

-Regarding Othello, there was a scene where he tells Tachibana, "I want to change," due to Ororon's death and his inability to do anything for Chiaki.

-Yotsuba left Othello and, upon saying goodbye, called him "Father" for the first time, saying, "Take care, Father."