English Name: Serena (last name unknown)
They changed Usagi's name to Serena because that was the equvilant to Selenity which is here Princess name. Usgai would translate into "Rabbit" Or as a name "Bunny" which didn't seem to fit as a good name. Princess Selenity is Usagi. For English purposes so people wouldn't get confused they changed her name to Princess Serena and her human name Serena. I spelled her name as "Selenity" instead of "Serenity" becuase the Japanese don't pronounce there "R" as the same sound as English speakers. Their "R"'s are pronounced as L's. So "Rei" in the NA Japanese Sailor Moon would be pronounced as "Lei-chan".