What Should I Do If I Become a Devil on the Way to Find My Sister?

Oliver is an ordinary swordsman of the Holy See of Light. He thought he would always be like this in his life, a neither good nor bad person, admiring the light and scorning the darkness. Until I become a devil... Only then did he understand that fairness was just a game played by the powerful. This novel and its characters are purely fictitious. Any similarity is purely coincidental and should not be imitated.