Review Detail of Juushirou in High Human in Crossed Worlds - A HP x DxD Fic

I was confused most of the time i was reading. I mean I expected in the first chapter to read about the mc actually getting reincarnated. But no it starts off 1000 yrs after with his ghostly sister in law and no background information. Just here is the mc and his wives. Where is the harem building the romancing each woman?