"You and 19 other students are the selected students to be the test subjects of a project created by the New Principal of Pasado High School, Kira-san. Kira-san themselves was just appointed as the principal of the school when a few days after the disappearance of the old school principal, Yasuji Kamada. Apart from Kira-san, there was one more person who worked with Kira-san on that project and that was Hito-san, the New Vice Principal of Pasado High School. He was also appointed as the vice principal of the school, along with the appointment of Kira-san and the disappearance case of the old vice principal, Daichi Kamada, who is also the younger brother of Yasuji. Approximately, can you and 19 other students solve the mysteries? Will they find something they never thought possible? and will they find a secret that has been hidden by the school for a long time? Or... what project did Kira-san and Hito-san have made?"