“If I can figure out what day Kayo Hinazuki disappeared, I can prevent the incident from happening.”
Satoru works out that “X-day” is before her birthday, but when he asks her what day that is, Hinazuki refuses to tell him because of something trivial that nevertheless put distance between them. So Satoru goes to the staff room and gets the answer from their teacher, Yashiro. After confirming that X-day is March 1st, Satoru pays Hinazuki a visit at her house to check up on her. But he finds Hinazuki beat up and locked in a storage shed…