The Island of Orcs / オークの島

Janice is a hero who defeated the Black Dragon, a demon dragon that threatened many countries with her holy sword.
Janice's achievements were recognized, and the king personally entrusted her with the task of defeating the Orcs.
The Orcs appear with the crash of a meteorite, and with their amazing breeding power, they take over the island of Ark, which is rich in mining resources.
The Orcs have kidnapped and raped many human women, and have been breeding repeatedly.
Janice, the hero of the holy sword, never doubts her own mission and ability, and bravely plunges into Ark Island. ----

And then. I'm not sure what to make of it.

What is their purpose? And what exactly is on this island ----?