This name is so cute. I imagine some of the sweet girls in mangas and anime that I grew up with, like Sailor moon and Hamtaru so this name is so lovely to me. In fact, if I ever go to Japan and marry a Japanese man and have a baby girl, I will definitely name her Hotaru after Hamtaru, my favorite children's anime show. It will always will be cute and innocent to me.
I took Japanese for two years in high school, and my teacher encouraged us all to take Japanese names to use in class. I used Hotaru, since I am a huge Sailor Moon fan and Hotaru (Sailor Saturn) is my favorite character. When I went on a two-week study tour of Japan in my senior year, I used the name at home with my Japanese host family. Even today, my best friend, who I met in the Japanese program at school, still calls me Hotaru in our emails. This is definitely one of my favorite Japanese names, and while it is rare it is indeed a real Japanese name.
Hotaru is a beautiful Japanese name. How cute it would be to call your baby a name meaning firefly! Maybe someone who is named Hotaru will be as adventurous and as captivating as their name. In America, I fear that this name would not get very good reactions. But no matter what this is really a lovely name. =D