Japan — on the coast of the Pacific Ocean, the [DxD] Team and their allies who fought against the Trihexa which threatened Japan now bore witness to the scene before their eyes. Trihexa was gradually being dragged into the sealing field—. After a retreat was issued to return to this coast, all members received news of the final battle plan. The higher ups of each faction prepared themselves for an eternal battle with Trihexa, and then set out for the Isolation Barrier Field—. Once inside, unless they defeated Trihexa, regardless of whether they were a god-class being or a Transcendent Being, they would not be able to come out. In order to defeat Trihexa, which was capable of repeatedly regenerating itself, it would require several thousand years, or even—.
Sona Sitri was standing on the coast in one corner while crying. She did not know that her ane , Serafall, would also depart for there. Not even a single word of farewell was conveyed to her.
“…Onee-sama…no, I hate this…. Why did you leave me behind and go ahead by yourself…? My dream…I also wanted you to see it, onee-sama…”
The sorrowful Sona Sitri wept without any of the visage that she normally had, but instead showed tears befitting a girl of her age. It was only natural. She was eighteen years old. As a Devil, she was still a child, and from now on, she would be waiting for an eternity without her ane, and a world without her ane.
At the same time, standing beside her to comfort her, Rias Gremory was in the same situation. Her ani  Sirzechs had also departed for the Isolation Barrier Field—. No parting words could be conveyed either. Her ani was Lucifer. The King of Devils, Lucifer. So, in order to protect the Devils, he made up his mind to participate in the eternal battle against Trihexa. However—. Her ani…he was also a Gremory. He was originally a Gremory. Even if he was called a Super Devil, he was originally a Gremory. It’s just that he was a gentle and strong person.
Yes, he was gentle and strong—.
No, precisely because of this, Sirzechs had such determination. Precisely because of his gentleness and his strength, he departed for the sake of protecting everything.
“…Onii-sama…you really are, hopelessly stupid…”
A stream of tears flowed down Rias’ cheeks as she conveyed her own thoughts—.
Soon, it would be her high school graduation ceremony.
…I am going to depart on a journey from there, and I originally hoped that you would see that moment….
This battle, and the scene before her eyes, it was something that Rias would not forget for the rest of her life—.
(Part 1 of 1) (7/8)
 ane: Elder sister.
 ani: Elder brother.
Continues on to Y Ddraig Goch & Albion Gwiber