A good story idea?

This story is about a husband and wife having triplets, and the mom is worried about their life, because she will have to put them up for adoption once they're born, because she can't pay for them and any extra 食 due to the economy, so she goes to a man named The Magic Man, who says he will tell their futures if they give them their three children, in which the two agree on. When he tells them their childrens futures, he signs a contract with the woman, who after a week when her three children are born, gives them to The Magic Man, who gives them to his grandmother to take care of. The three children grow up to be magical beings. But one day, the woman comes back for her children, but The Magic Man won't budge. Now, the three children go on quest によって the grandmothers orders, not knowing they have parents. But later in the series they do find out they have them.