Fate/Grand Order: Himuro no Tenchi - 7-nin no Saikyou Ijin-hen
The source material follows three girls — Kaede Makidera, Kane Himuro, and Yukika Saegusa — at Homurahara Academy, but has nothing to do with the efforts to restore the Human Order.
Fate/Grand Order氷室の天地~7人の最強の偉人編~ Fate/Grand Order x Himuro's World: Seven Most Powerful Great Figures Chapter