キズナイーバー - 舞台は、埋立地に作られた街・洲籠市。
かつては未来型都市として栄えたこの街に住む高校生・阿形勝平は、なぜか痛みを感じない不思議な身体を持っていた。
夏休み目前となったある日、勝平は謎の少女・園崎法子の手引きにより、痛みを共有する仲間「キズナイーバー」の一人に選ばれてしまう。
そして、同様に「キズナイーバー」として繋がれたクラスメイトたち。
しかし、彼らは本来なら仲良くなることのない別々のグループに属していた。
園崎は言う「これは、争いに満ちた世界を平和に導くための実験なのです。」
その言葉とともに数々の試練が彼らに降りかかる。
互いの傷を背負うことになった、少年少女たちのひと夏の物語がここから始まる!
Kiznaiver - Katsuhira Agata is a quiet and reserved teenage boy whose sense of pain has all but vanished. His friend, Chidori Takashiro, can only faintly remember the days before Katsuhira had undergone this profound change. Now, his muffled and complacent demeanor make Katsuhira a constant target for bullies, who exploit him for egregious sums of money. But their fists only just manage to make him blink, as even emotions are far from his grasp.
However, one day Katsuhira, Chidori, and four other teenagers are abducted and forced to join the Kizuna System as official "Kiznaivers." Those taking part are connected through pain: if one member is injured, the others will feel an equal amount of agony. These individuals must become the lab rats and scapegoats of an incomplete system designed with world peace in mind. With their fates literally intertwined, the Kiznaivers must expose their true selves to each other, or risk failing much more than just the Kizuna System.