Keychain | Black Clover (see variants)

Black Clover
Asta and Yuno are orphans raised in the outskirts of the Clover Kingdom. In a world where people are born with magic, Asta was born without any. In contrast, Yuno was born a prodigy with above average magic power and the talent to control it. Additionally, in their coming of age ceremony, Yuno receives a rare four-leaf clover grimoire, like the original Wizard King. On the other hand, Asta received a tattered grimoire where a devil lies within, a five-leaf clover grimoire.

The story follows Asta and Yuno as they crawl their way up the ladder of the Clover Kingdom's Magic Knights, in the midst of scrutiny by the nobles, to become the Wizard King. However, the title is only preserved for a single mage. Who will attain the coveted title of the strongest mage in the kingdom, Asta or Yuno?

Black Bull is one of the nine squads of the Clover Kingdom's Magic Knights. The squad is known for its destructive behavior and has been regarded as the worst squad of the organization. Like the other eight squads, Black Bull follows the orders of the Wizard King and will act according to his requests. All squads, including the Black Bull, perform missions all around the Clover Kingdom whether they are official or unofficial.

The Demon-Dweller Sword is an ancient Anti Magic Weapon. Asta finds the sword in a hidden room within a dungeon treasury. The sword has black markings on the blade and is mostly covered in dirt. The sword also has a heavily ornate hilt with a four-sided guard, a grip with a spiral design, and a sphere for the pommel. The sword is capable of cutting magic with its edges and absorbing other people's magical power. However, when it is used to cut anything else, it is reduced to a blunt sword that uses blunt trauma to inflict damage on the opponent.

(from Fandom Black Clover Wiki)