Hyperdimension Neptunia: Goddess VS Devil
In the midst of the Goddesses having to solve various problems within their nations, a sudden new threat forces them to rise above and protect their nations from total destruction. In this slightly more serious take, the Goddesses face the opposite of them, beings born from negative energy with the soul purpose of destroying the nations they were born in. Worse is, they are far stronger and seemingly unkillable, never mind that nothing is known about them.