Kagome is a priestess on her way to a nearby temple in place of her older sister, Kikyo, who's gone missing, and she unfortunately attracts the attention of a band of men. She escapes into the temple, prays to God that she won't be raped, and is found by a beautiful demon named Sesshomaru, who presents himself as a God. She makes a deal with him, only to realize he isn't a god but a shinigami, and he wants to corrupt her.

Hi I believe you're looking for Belovedstrangers Bound by Corruption rated MA, and it is complete.

Summary,

Inside every individual, darkness dwelled large or small. A young woman, cast under her elder sister’s shadow, was bent on proving her worth. A terrible threat hung over her village, giving Kagome the opportunity she had been waiting for. On a mission to save them all from the hearts of evil men, she journeyed to the Inu no Kami’s temple to beseech divine intervention. Instead, danger befell the headstrong woman. Rather than obtaining help from a merciful god, another stepped in to slaughter her enemies, but for a price. An Inugami did nothing for free.

They are also working on a sequel that is MA also but it is not complete.

Oh almost forgot, the original oneshot is in her oneshot collection A Smell So Sweet in chapter 2, again MA so no YIMS!

It is! Thank you. I couldn't remember the title for the life of me. I thought it had something to do with "sin" or "seduction."

You're welcome. Glad I could help