In Japanese folklore, a "tsukumogami" is an object that has gained a soul, becoming alive and self-aware. There are two types of tsukumogami: the mature "tsugumomo," who have developed through long years of harmony with their owners, and the aberrant "amasogi," premature spirits that are only born to grant the destructive wishes of certain people. Kazuya Kagami has never gone without his mother's obi after her death. Be it at home or school, he keeps it safe with him at all times. One day, he nearly loses his life when a wig amasogi attacks him. When all seems to be over, his treasured obi defends him, transforming into a beautiful girl. She introduces herself as Kiriha, a tsugumomo owned by Kazuya's mother. With Kiriha's arrival, Kazuya enters a reality he has never seen before, a world with gods and tsukumogami. [Written by MAL Rewrite]

In the Sun Kingdom, sunshine is part of its citizens' everyday lives, and rain is something that they have never even heard of. However, in a faraway land called the Rain Dukedom, the weather is reversed, and everybody has the power to create rain with their voices. Livius Ifrikia has conquered the entire world and expanded the Sun Kingdom's influence in the three short years since he was crowned king. Upon learning about the powers to create rain, Livius decides to marry Nike Remercier, one of the princesses of the Rain Dukedom. However, those outside the Sun Kingdom have spread a rumor that Livius is a cruel, ruthless, and tyrannical ruler, and as word reaches the princess, she begins to prepare herself for the worst. But when she finally meets her fiancé, Nike discovers that he is an entirely different person from what she originally expected. [Written by MAL Rewrite]

The Holy Grail is a powerful, ancient relic capable of granting any wish the beholder desires. In order to obtain this power, various magi known as "masters" summon legendary Heroic Spirits called "servants" to fight for them in a destructive battle royale—the Holy Grail War. Only the last master-servant pair standing may claim the Grail for themselves. Yet, the third war ended inconclusively, as the Grail mysteriously disappeared following the conflict. Many years later, the magi clan Yggdmillennia announces its possession of the Holy Grail, and intends to leave the Mage's Association. In response, the Association sends 50 elite magi to retrieve the Grail; however, all but one are killed by an unknown servant. The lone survivor is used as a messenger to convey Yggdmillennia's declaration of war on the Association. As there are only two parties involved in the conflict, the Holy Grail War takes on an unusual form. Yggdmillennia and the Mage's Association will each deploy seven master-servant pairs, and the side that loses all its combatants first will forfeit the artifact. As the 14 masters summon their servants and assemble on the battlefield, the magical world shivers in anticipation with the rise of the Great Holy Grail War. [Written by MAL Rewrite]

Specials included in the Blu-ray and DVD releases of One Punch Man.