Due to his good-natured personality and a streak of bad luck, Orifushi Shiki is forced to enroll in St. Lucimantz Academy, notorious for its delinquents.

Having lived a life far removed from delinquents before his enrollment, Shiki finds himself at St. Lucimantz Academy akin to a herbivore thrown into a cage of carnivores. Shiki himself was acutely aware of this, but his moderate sense of justice and his exceedingly good-natured personality proved to be his undoing, leading him to be targeted by one of the countless delinquent groups populating the school.

For a year thereafter, Shiki was bullied by the delinquent group and endured hellish days. However, one day, a near-collision with the academy's toughest delinquent girl—Kohinata Karin—in front of a vending machine triggers a drastic turn in Shiki's school life.