As the title suggests, there are seven key sins. Those who have caused enough evil in their lives and their soul's are condemned to Hell, that soul will suffer for their biggest Sin. Each Sin is connected with a color and an animal. It is this same color that appears on the string that emerges from the fingertips of our souls within the Spirit Realm that signifies our Soulless. This is to say that every Soulless has a specific Sin. curiously enough, like everything in this world, there is a yin to every yang. In this case, there are Seven Heavenly Virtues. To whom these apply, I can not be certain, but if Axel's Theory is correct, then the Seven Heavenly Virtues would apply to the Nobodies as a mirror to the Soulless.