Ladder of Heaven

Heaven's Bridge is a weapon stipulated as the strongest and evilest.

Description
Although Heaven's Bridge remains a mystery, it has been revealed that the reconstruction during the ten years after the war mankind speaks proudly about is nothing more than a mere weapon specialized for massacre. Heaven's Bridge, given the name of the strongest and evilest weapon, is what connects heaven and earth. Born from the Great Gastrea War, it is a super weapon that saw the defeat of humanity.