Saeko is a young lady that mysteriously appeard around the limbo between Heaven and Hell that is present in this story. She has a long white hair, dark eyes, a pale skin and a black halo. Disguised between people, she observes how society and people interact with each other.
Osian is one of her only friends in the whole story since hes the one who started with this thing of trying to find from where she came from, if she was or from hell or from heaven, acidentaly ending up feeding - .... . / -.. .. ...- .. -. . / -.. . ... - .-. ..- -.-. - .. --- -. .-.-.- more and more, like naming her, taking her to Heaven, to Hell, meeting and killing different entities. All of that was a mistake, and it is all his fault.
The Divine Destruction is the name given to the effects of Saeko's presence in the world. It was a mistake, and she shouldn't be there. Osian was the one who made this mistake even worse by trying to find the place she actually comes from, which is neither hell nor heaven. She is the observer of this world, a true --. --- -.. .-.-.- I might say, and showing her how the world truly works caused this destruction. After all, who accidentaly showed her the world? Osian. Also, answering the last question: Osian's suffer is living, which means that it is not 100% related to The Divine Destruction.
Interesting... what is THE DIVINE DESTRUCTION? And (if it is THE DIVINE DESTRUCTION,) what are they doing to Osian? And what "suffering" happened to Osian that would prompt this?