Never heard of a kid named Hotaru, but there are parents making up names these days, so you never know what they might call their kids. Japan hasn't standardized their names quite the same way France has.
Hotaru is a Japanese name & a friend of mine has this name but she writes it in katakana. Odagiri Hotaru is a Japanese voice actress.Just because you`ve never met a Hotaru before doesn`t mean that this isn`t a name.