Muzan had a favourite in Demon Slayer (and his actions confirm who)

In light of the upcoming season of Demon Slayer, the anime series has reached a level of popularity unlike ever before. While fans and viewers of the series look back at all the events to date, it acts both as a refresher and as context for the follow-up. During such a revision, a certain fact has come to light that opened the discussion of a possibility.

While Muzan's behavior towards the Lower Moon demons from the series was very transparently shown, a certain individual among them was treated differently. The individual in question is the Lower Rank Five demon, Rui. While Muzan may not have shown it directly, his actions regarding Rui hint at a lot about his biases.

Disclaimer: This article is a speculative theory and reflects the author's opinions.

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Implications that Muzan favored Rui more than the other Lower Moons in Demon Slayer

Featured in the Demon Slayer: Mt. Natagumo arc, Rui was the first member of the Twelve Kizuki with a Blood Demon Art to be introduced in the series. His introduction was the first instance when fans were introduced to the concept and depths of Muzan's Twelve Kizuki hierarchy system.

While the Lower Moon demons from the Demon Slayer series are considered weaker, even by Muzan, as he killed them off instantly out of rage, Rui felt like an exception to him. It was also Rui's defeat at the hands of Tanjiro that triggered Muzan to lash out at the other Lower Moon demons and kill them off, ruining the balance of the hierarchy system he created.

In the series, Muzan values his own blood, rarely sharing it with other demons. Yet Rui was allowed to freely use it and create demons of his own, as shown in the anime when he created the spider family that fought against the slayer at Mount Natagumo. This also meant that Rui shared his powers with them, implying his relief from the duty of climbing up the ranks.

One of the reasons for Rui's treatment could have been that Muzan saw a reflection of himself in Rui. Similarly to Muzan, Rui was also a sick boy on the verge of death. Despite Muzan denying and avoiding it, he still reminisces about memories of when he was a human.

While Muzan might not have adored Rui, his fondness for the latter may have stemmed from deep within his subconscious. The similarities in the beginning of their journey as demons might be what has led to Muzan's bias towards Rui, compared to the other Lower Moon demons, with his death serving as the last straw.

While the Lower Moon demons are stronger than normal ones, they have failed to produce results for Muzan, whether it be killing the Hashira or the slayers, or even finding the Blue Spider lily. Due to his fondness towards Rui, his death might have been an eye-opener for Muzan, leading him to abolish the entire Lower Moon system by eliminating them.

As Muzan was a stickler for rules, his drastic actions can be justified as to why he decided to take the step. Even after the incident of the Demon Slayer: Entertainment District arc, Muzan made a case to remind all the Upper Moon demons as well of what they are tasked to do and what happens if they fail, presenting the Lower Moons as an example.

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Final thoughts

The Lower Moon from Demon Slayer gathered at the Infinity Castle after Rui's death (Image via Ufotable)

Theoretically, justifying Muzan's actions is not an optimal possibility due to the screentime and information available for all the Lower Moon demons in the series. Only Rui in the Mt. Natagumo arc and Enmu in the Mugen Train arc were featured in the main series.

As Demon Slayer approaches the release of its latest installment, the Infinity Castle arc, fans eagerly await the final clash between the demons and the slayers.

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