A last name that can mean Defender Of?

I'm writing about a character and her name is Yasu (which means peace) and I've been trying to find a last name that fit her and her name. So If anyone can help me, please I would love to take an suggestions.

Look interesting, I wish to help you, if possible.

"Morito" is male first name means "Defender".
But last name for female?

"Morita, Moriya, Morimiya"?
They protect "field, home, shrine".
"Kubo" means "Keep long time".
Those are common Japanese family name.
I think "Morimiya Yasu" is not so bad.

BTW, Yasu is rare female personal name.
Nickname for Yasuko or Yasuyo is often.
Yasu of "Yasu Megumi"(TV personality) is family name.
http://www.harmonypromotion.co.jp/yasu/top.html
So you can give her "Yasu" for family name.
Just now, I can't think of any good female personal name means "Defender".
How about this?

OK, "last=family, first=personal", I'm confused because of reverse the order in Japanese (^-^;

The first name Yasu is usually a male name, it's too weird for a girl's first name. You should change it to Yasuko or something like that.