This story starts at a school called "St. Maria High School", a school where our main protagonists attends. Rumors say that this school has been included in some murder cases since the pass 3 years. Satoshi Sakibara attends the first day of classes and meets three girls that happens to be that they are triplets. They are Yukari, Hikari, Akari Kusaragi. Together, they investigate if the rumor will bring them to the school's deep dark secret that nobody knows...