I'm joining in on the "side" of recommending that if you do name your child Nagisa you do it as a middle name. That way you get to keep your original idea of calling the child Nagisa, you get to use that name around the house easily and she won't have to face as much embarrassing situations in life due to her name.
Also (and more in jest): are you sure? Don't you think it's a bit risky? It's not every day you get a son-in-law that just so happens to be such a good guy that miracles are given to him.
