Heroic Conceited Son-in-law

*Since he got memory, He lived only with his sister.
Even when he became the son-in-law and mocked by others he didn't felt despair, because he had his wife and sister loved him.
Until that day, when his sister was dying because of seriously illness,and his family didn't want to spent even one coin to save her life.For the first time he felt despair.
When he was running around to save his sister,his true father had found him...
Who would know his true identity was the son which belongs to the richest family?!