Saigo no Yakusoku no Monogatari

Become the head of the Messiah knights and save your country from complete ruin. There is only one way to turn the situation around; activate the last source of magic by exchanging the Last Vows. Yet before you can use such powers, you have to battle the massive steel monsters that infest your skies and are killing off your troops and ordinary civilians. Create perfect strategies and be careful when you pit your people against your foes, because you can't revive them once they die.Everybody has a gauge, this determines the skills you can use, but if you use it up, your warrior dies. Use your power to protect your people and in some way, choose who to sacrifice.