A fake brother meets a rich sister,
The older brother owed a huge debt and was unable to repay it, so he had to pretend to be the older brother just to get money.
Who knows if his care and love were misunderstood by her, and her love grew out of a conspiracy, whether it was fate or a debt.
My brother is a mature uncle type, and my sister is pretty and cute.
The novel has ups and downs, and is generally light-hearted.