Quick Transmigration: My Sister-in-Law Helps Me Win Over the Spirit Lord of Another World

The cold and arrogant Spirit Lord meets the nemesis fate has ordained for him. What began as a tug-of-war over mutual interests turns into a bond of unspoken understanding, with the two warming one another's hearts.

After spending her whole life struggling through hardship and living for others, the heroine's soul transmigrates to another world. She no longer wants to be timid and deferential, worrying about everyone and everything but herself. In this life, she'll bravely do what she wants, flirt with the most handsome and powerful man, and become the freest, most carefree person she can be.

No angst from start to finish, just sweetness all the way through.