User blog comment:B214/High School DxD BorN episode 1 review/@comment-3965848-20150407194754/@comment-26216310-20150407212010

Yeah I remember that too. Magic was used to create an artificial moon in the underworld. I think rias is the one who explained it to issei if I'm not mistaken. She did explain while they were on the train tht I do remember, don't remember if something led to her explaining or if she did it just for the sake of the readers. I think issei asked on it or said something to have her explain but idk. In any case, I don't think it was of any importance and it was more like a bit of extra knowledge and bg to the show to add more character :3