What If A Otaku Become The World Savior?

In the World of Erden
which lived by Seven races which is humans, Elves, Half beasts, Orcs, Demons, Dwarf and Fairy creature once live in peace and co-existing with one and another.(Except for demon race)

But,
out of nowhere the unknown race called them self as The Ancient rise and claim to invade World of Erden as Orcus as their leader and commander.Their invasion spread in a blink of eye and they had already invade a quater of Erden in a month.

After a war between this lost race and the alliance of six race;Or being called as Enden Unity occurs about half of the year.The ancient overpower the Erden Unity with their strategies and man-power.Before they noticed the Ancient had invade half of Erden.Not so long after that The alliance was connered to the brink of defeat.

When they in the edge of defeat.
Suddenly, The great Sear of Fairy race show an Holy scroll which be found in Holy Libary.The scroll told that
[One day, the Unknown race will tried invade the World of Eden that leaded by the reincarnation of the seventh god; The Lost god.The Scroll said that reincarnation of the Seventh god can be defeat by the chosen Hero by the six gods.He, then will defeat The seventh god with aids from seven brave warrior .But no one know when and where the Heroes be summoned to this world.]

Which left which no choice the Erden Unity decide to hold back and fight the ancient race until the reincarnation of six god being summon.

After Hearing such information,
For some reason,Orcus was overjoyed and recalled all of the ancient race to fall back to their territory which including the half of Erden that has been invaded.He sent his men to deliver his message to all other race :

"To all six race that live in this realm,
I,Orcus will not attack and invade this world from now on.
BUT,
I will wait until your Six god reincarnation to be summon to this world.
I ;Orcus will keep the half of Erden which I invade until your Hero and his companions defeat and take it back from me."