"Jukan" is a manga series that revolves around a post-apocalyptic world where humanity faces extinction due to the emergence of monstrous creatures known as "Ju." These beings, born from human corpses, possess immense strength and a relentless hunger for destruction. The story centers on a young man named Shuu, who survives in this desolate world alongside his childhood friend, Rina. Shuu is no ordinary survivor; he harbors a unique ability to temporarily transform into a Ju, granting him extraordinary combat prowess. This power, however, comes at a cost, as prolonged use risks losing his humanity and succumbing to the monstrous nature of the Ju.

The narrative begins with Shuu and Rina scavenging for resources in the ruins of civilization, constantly evading the Ju and other hostile survivors. Their lives take a dramatic turn when they encounter a mysterious organization known as the "Guardians," who are dedicated to eradicating the Ju and restoring order. The Guardians recruit Shuu, recognizing his potential as a weapon against the Ju. As Shuu becomes more involved with the organization, he uncovers dark secrets about the origins of the Ju and the true nature of his own abilities.

Throughout the series, Shuu grapples with the moral implications of his powers and the fear of losing himself to the Ju. His relationship with Rina serves as an emotional anchor, providing moments of humanity amidst the chaos. The story explores themes of survival, identity, and the thin line between man and monster. As the conflict between the Guardians and the Ju intensifies, Shuu is forced to confront his own inner demons and make difficult choices that will determine the fate of what remains of humanity. The manga balances intense action sequences with introspective moments, creating a compelling narrative that delves into the psychological and emotional struggles of its characters.