Age of Wild Beasts

The human heart is a huge wild beast, sometimes it is despicable and cowardly, sometimes it is bold, sometimes it is peaceful and contented, sometimes it is greedy and insatiable. The era of wild beasts was ended by human technology at a huge cost. Wild beasts that were supposed to be extinct reappeared in the "Era of Recovery" when development resumed, causing serious damage to human civilization. However, humans have never known the reason for the birth of wild beasts.