A fully armored swordsman;
a young man in a top hat, holding a spear in reverse grip;
a knightly girl poised to shoot an arrow;
a mounted warrior gripping the reins;
a mysterious, wise old man;
an assassin wearing a skull mask;
a bloodthirsty beast, raging with ferocity;
Putting away the Class Cards floating around him, Illyasviel said frankly:
"Now, the future is in my hands!"
The log of humanity's salvation by Illyasviel von Einzbern, of a family fallen from glory for a thousand years.
Simply put, this is the Foundation of Humanity in an alternate timeline.
(P.S. The protagonist may suffer a bit in the early stages. It's a gradual progression, and they'll become stronger in the middle and later stages.)