Private Haritani Academy—
"Extraterritoriality" and "Male Supremacy" run rampant in this closed-off space.

Under the banner of "student self-governance," students belonging to various committees—led by the student council—hold sway over the general student body. Among the general students, girls are referred to as "lower-tier students" and are expected to "obey absolutely" the commands of those in higher positions.
In this school, a place following outdated, harmful traditions, a strange disappearance has occurred.

You take on the role of the protagonist, Isugi, the head of the disciplinary committee. Your task is to gather information by questioning various students, using informants, and conducting your own investigations to uncover the truth behind the mystery.
The Disciplinary Committee holds the authority to impose punishments on students—a power known as the "Student Guidance and Disciplinary Authority."
The more you used every illegal means at you disposal to get closer to the truth of the incident,
the more you found yourself unavoidably drawn to the student council—led by the quiet yet formidable student council president, Sakuragi Hayato.
It wouldn’t take long for you to realize that the darker force hiding beneath the surface—what some called the "System"—had, in fact, spread its influence over the entire school.

[Translated from dlsite]