In the world of Seraph of the End, most of humanity has perished due to the collapse of the world, and vampires rule the surface. In Japan, the Japanese Imperial Demon Army was formed, continuing the fight for a counterattack against the vampires and the restoration of humanity. At the center of this is Guren Ichinose. While forced to obey the Hiragi family, Guren chose his own path to protect his comrades, acting alongside Shinya Hiragi, Sayuri Hanayori, Mito Jujo, Shigure Yukimi, and Norito Goshi. Though they differ in status and personality, they have built strong trust through long years of battle. Eventually, the existence and plans of Mahiru Hiragi lead them into the depths of the world's secrets. Vampires, Cursed Gear, the Hiragi family, the Mikado-no-Oni, and the "Seraph of the End." The power to save humans simultaneously held the danger of destroying the world. Guren prioritizes protecting his friends above all else while facing unavoidable tragedies. Even after the world collapsed, the battle did not end, and they continue to seek a way to survive while holding onto their respective beliefs. To Guren, his comrades are not just brothers-in-arms. They are precious people he must protect even at the cost of his life, and losing them is the one thing he can never accept. That determination remained as a strong will to protect them, even after reaching for a power that defied the laws of the world. The path of continued protection.

Just before the world's collapse, Guren and the others headed to Mahiru Hiragi, where they faced a grave truth. In the battle, Shinya Hiragi, Sayuri Hanayori, Mito Jujo, Shigure Yukimi, and Norito Goshi lost their lives. Shinya tried to protect his friends until the end, Mito also continued to fight for her comrades, and Goshi did not flee despite his fear. Sayuri and Shigure also stood their ground with Guren until the end, and the five died leaving behind their respective feelings. Despairing at losing his friends before his eyes, Guren utilized the secrets of the "Seraph of the End" and the world revealed by Mahiru, making a forbidden choice to bring the five back. Prepared to sacrifice his own life, Guren activated the power of the Seraph of the End, and through that power, resurrected the five who had died. The resurrection was not a natural miracle, but a phenomenon deeply tied to the collapse of the world. Although the five returned with living bodies, they do not recognize the fact that they died once. Fearing he might lose them again, Guren does not speak of their death and resurrection, treating them as if nothing had happened. Shinya, Mito, Goshi, Sayuri, and Shigure fight alongside Guren once more. However, Guren alone continues to carry the burden of the fact that they died once and that he brought them back with forbidden power. As the battle against vampires, the power of Cursed Gear, the Hiragi family's conspiracies, and the plan surrounding the Seraph of the End continue, the resurrection of the five complicates the fate of the world. To ensure he never loses his comrades again, Guren continues the fight to protect their lives and their future.