The Demon Slayer manga and anime have captured the hearts of countless fans worldwide, propelling the series to extraordinary heights of popularity.

The story follows the journey of Tanjiro Kamado, a young boy whose life is turned upside down when his family is murdered, and his sister Nezuko is turned into a demon. 

According to the series’ lore, demons are not creatures of birth or creation but humans who have been irreversibly transfigured. Every demon has varying motivations on why they became a creature of the night. Some humans accepted the offer to become a demon, while some were forced into becoming one.

Within the series filled with malevolent beings, it is important to discern the primary demon in the series. This character holds exceptional significance, as their pivotal role drives the narrative forward.

Warning: Major spoilers for fans who have not read the manga and those who have yet to watch the anime.

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Why is the first demon in Demon Slayer so crucial to the story of the series?

Demon Slayers' Nezuko
Credit: Aniplex, Koyoharu Gotoge, SHUEISHA, ufotable

Technically, the first demon to appear in the series is Nezuko. After the Kamado family was slaughtered in the anime’s first episode and the manga’s first chapter, Nezuko was transformed into a demon and tried to kill Tanjiro.

Amidst the fierce battle between the siblings, Giyu Tomioka, the Water Pillar, interjects, intending to sever Nezuko’s head. However, Tanjiro intervened and saved his sister. Uncertain of the appropriate course of action, Giyu reluctantly resorts to his instincts, dispatching the Kamado siblings to the Sagiri mountains, where they seek the guidance of Giyu’s former mentor, Sakonji Urokodaki.

Demon Slayer main antagonist Muzan Kibutsuji
Credit: ufotable

However, if we’re talking about the first demon to exist in the series. In that case, the honor belongs to Muzan Kibutsuji, the main villain of the series who murdered the Kamado family and pushed Tanjiro to begin his journey as a Demon Slayer.

Revered as the Demon King and serving as the principal antagonist throughout Demon Slayer, Muzan’s transformation occurred a millennium ago during the Heian Era. Born with a terminal illness, the young Muzan faced an imminent demise until an experimental procedure altered his genetic composition, saving him from the clutches of death.

Infused with newfound vitality, Muzan embarked on a nefarious crusade, spreading his affliction across Japan. Muzan’s rise to power brought forth tragedy and torment. However, it also started the campaign of the Demon Slayer Corp, a group of warriors with the sole purpose of ridding the world of demons.

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READ MORE: Demon Slayer watch order: How to watch the anime and movies in chronological order