Akihisa Yoshii has been admitted to a special academy where your grade on the placement exam determines your status. For example, the Class A students get lounge seats, personal laptops and special tables. Class D students get a pretty nice, normal classroom setup. But Akihisa finds himself stuck in Class F: A rundown, dirty classroom with broken coffee tables for desks, partially shattered windows, tatami mats covering the floor and a teacher who doesn't seem to care anymore.
Some of the main cast of characters gets introduced: The class rep, the voyeur, the trap, the violent tomboy, and the surprisingly smart girl who is only there because a sickness forced her to miss the placement exam and netted her 0 points. After introducing themselves, the class rep, Yuuji Sakamoto, decides to immediately declare war on class E and take their room.
The war is fairly straightforward: the students each have summoned monsters that have power derived from their test scores. The better the score on a particular subject, the more powerful the monster will be. Students have an option to recover their monster's HP by taking a quick test on a particular subject, but if any monster loses all HP then the respective student is dragged off to detention for "supplementary lessons."
At first, the students of Class F find themselves backed into a corner because their scores are just that low. But the class rep reveals that he had a couple of secret weapons up his sleeve. The first is the revelation that Akihisa wields a special type of summoned monster that can supposedly react to Akihisa's own physical signals, but when that gets eliminated due to his incredibly low test scores, Yuuji pulls out his final trump card: Mizuki Himeji. She took a math test so quickly and scored so well that her monster alone beats the remaining monsters of Class E combined.
The students of Class F celebrate their victory, but it becomes a short celebration when Yuuji reveals that he refused to move into Class E's room because he has a plan to take over Class A's luxurious room. Before he can lay out his plan, Class A's own representative appears at the door to pre-emptively challenge Yuuji and Class F to a battle.