This is a good story, definitely recommend.
I also recommend Oracle by Planeshunter. It's an DxD fanfic where MC was inserted into a last devil heir with the ability of precog. His peerage comes from different anime/games/fics. This a harem done right with Sona as the main focus. I guess it's also around a 100k+ words or so, just binged it this morning till now.
Ked18