My childhood friend was a werewolf?!

◇◇ 17-year-old Shin Yuri, who started attending high school, finds out from her childhood friend Taehyung that he will be transferring to ◇◇ High School the next day. She exchanges letters with him and meets him again in the same class on the first day of the new semester. But then, just for a moment, she sees the news: every day, a human body is found in a nearby mountain?? What's going on?