Exam Summoning Battle (試験召喚戦争 Shiken Shōkan Sensō) is a system used by the Fumizuki Academy that involves all the students being able to summon beings, often referred to as Shoukanjuus. Shoukanjuus are then used by the students to battle each other. For an ESB to begin, a teacher must be present to supervise the battle. The teacher summons an ESB field, a place only Shoukanjuus can enter. The Shoukanjuus then gain attack power proportional to their summoner's last test score on the ESB field subject. The ESB field subject is dependent on the teacher supervising the battle. As the shoukanjuus battle each other, their attack power slowly drops. Once a shoukanjuu's attack power reaches zero, that student is declared KIA and must take remedial classes. A running gag in the series includes the remedial classes teacher, Soichi Nishimura dragging away KIA students, wherever the ESB might be. A student can recover points by taking tests in between battles. During these recovery tests, a student can take as many tests as they can in order to raise their attack power. Once a class claims victory, they can get new school materials, switch class facilities if they are from a lower class, or request that no changes be made.
It is later found in the scavenger hunt, that there are iron bracelets that can summon their own ESB field for any subject. It turns out that only idiots can use these bracelets and only Yoshii can use it. Later on in the series, Yoshii uses it to battle class 2-A but it breaks because he becomes too smart to use the Iron Bracelet.