Shinobu Sensui

Shinobu Sensui was Earths Spirit Detective before Yusuke Urameshi. According to Koenma he was the natural choice he was gifted with amazing spirit awareness strength and a strong moral sense of right and wrong. Sensui was very clearcut and adamant about his moral codes. Humans were victims so he had to protect them. Demons were evil he had to kill them. In time he met Itsuki who asks Sensui give him another day to live first so he can watch the finale of his favourite TV show. Hearing something so human coming from a demon Sensui laughs and spares Itsuki. By hanging around Itsuki Sensui realized that not all demons were evil. However his attitude towards humanity didnt change until one fateful night.