Very cliche story.
Tsushima Satsuki - the product of his parents who favored boys over girls, but he didn't expect that he would be a loser and a premature baby. He was thrown into his hometown in the countryside in anger and allowed to destroy himself.
Tsushima Fuko - the doted sister of her parents, a princess who was raised rich. Under the training of her parents, she successfully caught a golden husband, and she is a veritable Cinderella.
This is a battle between sparrow and phoenix, black and white swan.