With another Wave happening in a week, Naofumi Iwatani and his party have no time to waste. However, when bat familiars raid Lurolona Village and the Wave countdown comes to a halt, the Four Cardinal Heroes reconvene with the queen, Mirelia Q Melromarc, for a quick briefing. The queen presumes that the odd occurrences are linked to the Spirit Tortoise—a threatening creature that has awakened from its slumber, back to cause havoc once again. A plan to put the Spirit Tortoise to rest is devised—but out of the four men, only the cursed Shield Hero agrees to help.

The Four Cardinal Heroes are a group of ordinary men from modern-day Japan summoned to the kingdom of Melromarc to become its saviors. Melromarc is a country plagued by the Waves of Catastrophe that have repeatedly ravaged the land and brought disaster to its citizens for centuries. The four heroes are respectively bestowed a sword, spear, bow, and shield to vanquish these Waves. Naofumi Iwatani, an otaku, becomes cursed with the fate of being the Shield Hero. Armed with only a measly shield, Naofumi is belittled and ridiculed by his fellow heroes and the kingdom's people due to his weak offensive capabilities and lackluster personality. When the heroes are provided with resources and comrades to train with, Naofumi sets out with the only person willing to train alongside him, Malty Melromarc. He is soon betrayed by her, however, and becomes falsely accused of taking advantage of her. Naofumi then becomes heavily discriminated against and hated by the people of Melromarc for something he didn't do. With a raging storm of hurt and mistrust in his heart, Naofumi begins his journey of strengthening himself and his reputation. Further along however, the difficulty of being on his own sets in, so Naofumi buys a demi-human slave on the verge of death named Raphtalia to accompany him on his travels. As the Waves approach the kingdom, Naofumi and Raphtalia must fight for the survival of the kingdom and protect the people of Melromarc from their ill-fated future.

Throughout history, an elite group of shrine maidens known as Toji have saved the world from Aratama, strange and malevolent beings bent on destroying humanity. In modern times, these warriors have been assigned to a special police squad to exterminate Aratama. The government has also set up five elite schools across the country to provide young girls the necessary sword fighting skills to eradicate these monsters and eventually join their fellow Toji in protecting the world. A student of one of those five schools, Kanami Etou is chosen to represent Minoseki Academy in a sword fighting tournament, where she meets the mysterious Hiyori Juujou. Although Kanami and Hiyori rise to the top of the tournament, their battle takes an unexpected turn, throwing the world of the Toji into chaos. Likely that the Toji are facing betrayal from within, the two are forced to flee the tournament, clashing with former comrades on the way.

An original anime advertising Urawa City in Saitama, Japan.