A Soul to Touch by Opal Reyne

All Mayumi ever wanted was to hunt Demons.

After being discharged from the Demonslayer guild, Mayumi chose to isolate herself within the forest. The best place to hunt and kill Demons. But, one night, she’s surprised when a different monster is lured by her baits.
Just before she unleashes an arrow that’s aimed to kill, Mayumi pauses. She realises she’s seen that skulled, feline face before and that it had once saved her life.
All Faunus ever wanted was her.
After the Demon King cracked his skull, Faunus returns to watch over the only human he has ever cared for. He knows what his future holds, she would never become his bride, but he wants to spend what remains of his life protecting her.
He never expected that she would ever befriend him, or that she would openly desire him. She’s as fiery as her burning passion, and he’s desperate to let her consume him.
But his time in this world grows short, and Faunus doesn’t know how he can be with Mayumi when he knows nothing will save him.