While passing in a prep school, he suffered a severe case of diarrhea for 3 weeks. Believing he had not long to live, he wanted to leave some evidence that he had lived, through doing something that he liked as a child: working on manga. He was determined to create one work of manga in what he thought were his last months. As Nagai prepared for the task, he went to the hospital, where he was diagnosed with catarrh of the colon, and soon healed. But this was a turning point in his life: convinced that he would continue working on manga, he stopped attending school after three months and started living as a ronin.
