Entity from the past

I have been around from times even unknown to The boy in purple, I am old although I may seem young I am a crow, a voice and just a particle all the same. There was a time when I took care of a Robin another when I was the sibling to a butler, I have spoken to the smile many times and to the being yet to show its self. Although there is no name for me in the human tongue I have take likening to the bright little bug that comes out at night and have also taken a likening to the Japanese language so you can call me Hotaru.