At one point in time, Mitamura contracted some sort of disease.
The trio would come to cause severe damage to Kuwabara, who refused to kill them since he knew they were innocent humans (before the actual fight, Kuwabara had a dream about their ordeal).
Kazuya Hatanaka is Kurama's stepfather, having marry widow Shiori Minamino. In the manga, Kazuya met Shiori during the time she was at the hospital and the two started dating.
In the anime however, he is first mentioned in the Black Chapters saga by Kurama.
In high school, Togashi joined the fine-arts club and later enrolled at Yamagata University, studying education in hope of becoming a teacher.
It was during his years in college that he submitted some of his first manga to the Shueisha publisher.