Monsters known as "Horrors" have invaded the world, entering through gates from the Makai Realm of Darkness. These corrupt, demonic creatures have the ability to seize human bodies and feed on their souls. Citizens who are out past sunset will likely never see the sun rise again, but those who live in the capital city have no need to worry—they are protected by a spiritual force field created by the sorcerer group Onmyouji. In possession of legendary armor, the Golden Knight Raikou proclaims that he will protect everyone from the Horrors. Accompanied by his attendant Kintoki and the mysterious Makai Alchemist Seimei, he strives to become a formidable Makai Knight, but Raikou is ill-prepared to handle the side effects of the armor. Disappointed by his own shortcomings, he sets out on a journey of self-discovery to master his weaknesses and prove his worth. [Written by MAL Rewrite]

Corruption looms over the prosperous Russell City, where manifestations of negative emotions called Horrors cause chaos and mayhem. The Makai Order is the last bastion of hope against these unholy creatures. Using several small businesses as fronts, they deploy powerful Makai Knights and magical Makai Alchemists to combat the Horror threat. Within this secretive order, the highest rank of Golden Knight has been bestowed upon a large, powerful man named Sword, granting him use of the Garo armor and blade. He alone knows of a plot that threatens the entire Makai Order, with his only hint being the phrase “El Dorado." While fighting a Horror, he encounters Sophia "Sophie" Hennis, a teenage girl whose brother's disappearance years ago is also linked to the same phrase. The two agree to work together to uncover the truth behind "El Dorado" and the disappearance of Sophie's brother. [Written by MAL Rewrite]

Off-duty Japan Self-Defense Forces (JSDF) officer and otaku, Youji Itami, is on his way to attend a doujin convention in Ginza, Tokyo when a mysterious portal in the shape of a large gate suddenly appears. From this gate, supernatural creatures and warriors clad in medieval armor emerge, charging through the city, killing and destroying everything in their path. With swift actions, Youji saves as many lives as he can while the rest of the JSDF direct their efforts towards stopping the invasion. Three months after the attack, Youji has been tasked with leading a special recon team, as part of a JSDF task force, that will be sent to the world beyond the gate—now being referred to as the "Special Region." They must travel into this unknown world in order to learn more about what they are dealing with and attempt to befriend the locals in hopes of creating peaceful ties with the ruling empire. But if they fail, they face the consequence of participating in a devastating war that will engulf both sides of the gate. [Written by MAL Rewrite]

Several months have passed since the infamous Ginza Incident, with tensions between the Empire and JSDF escalating in the vast and mysterious "Special Region" over peace negotiations. The greed and curiosity of the global powers have also begun to grow, as reports about the technological limitations of the magical realm's archaic civilizations come to light. Meanwhile, Lieutenant Youji Itami and his merry band of female admirers struggle to navigate the complex political intrigue that plagues the Empire's court. Despite her best efforts, Princess Piña Co Lada faces difficulties attempting to convince her father that the JSDF has no intention of conquering their kingdom. Pressured from both sides of the Gate, Itami must consider even more drastic measures to fulfill his mission. [Written by MAL Rewrite]