When the world reached the brink of destruction, scientists stepped in to solve the problem. The answer was Gabriel, an immortal, synthetic human known as a Seraph. The result of illegal human experimentation, Gabriel is wielded as an international weapon, a super-soldier with engineered immortality. Without fail, Gabriel executes his orders with no thought or remorse. Seeing his obedience as heartlessness, the World Council Committee decides to test Gabriel and his humanity. Sent to an elite academic institution in his home country, Gabriel meets his true his classmate, Ken Haru. A pillar of society and the Ken's future patriarch, Haru is the untrained, still-human version of the young man called Gabriel. A mirror of each other, the two could have been brothers in another life, but now, Haru and the world he represents is a dangerous temptation. To prove he can be trusted with humanity's salvation, Gabriel yearns to give into his heart's deepest desires and enter Haru's world. But to enter Haru's world would be to end it. Torn between the life he could have had and the life he has to lead, Gabriel must decide which price he is willing to pay.