According to http://www.wikimoon.org]Project Wikimoon, http://www.wikimoon.org/index.php?title=Haruka]Haruka doesn't have any known family or backstory. http://www.wikimoon.org/index.php?title=Michiru_Kaiou]Michiru appears to be the same.
I can't find it right now, but I believe that Haruka was activated during one of her races, when a daimon was made out of her bike. I don't know about Michiru.
I can't find it right now, but I believe that Haruka was activated during one of her races, when a daimon was made out of her bike. I don't know about Michiru.