※NOTE：This article includes spoilers.
This time, We would like to summarize the hint “You are the only bad mark of my clan” drawn in episode 97 of the manga Demon Slayer.
Contents
The beginning is …
A word that Kagaya Ubuyashiki gave to Muzan Kibutsuji when he received a report that he had defeated the sixth of upper rank demon.
However, Muzan Kibutsuji is a demon.
Why is it said that it is “the only bad mark of my clan”?
Time is the Heian period
The story that leads to the answer is depicted in episode 127.
Muzan was originally a human being and was said to die before he was 20 years old.
In order to prolong his life as much as possible, doctors in the Heian period seemed to have become a demon who wants human blood and flesh as a result of formulating medicine to obtain a tough body.
Therefore, there is a time when he was a human being Muzan, so it is not without possibility.
When facing Kibutuji in Ubuyashiki house.
The story goes on, and in episode 137, the details of this story are told.It was when Kibutuji appeared in the Ubuyashiki house.
Kagaya Ubuyashiki said, “You and I have the same lineage,” and said that Kibutsuji was the same family as the Ubuyashiki before becoming a demon.He also said that the reason why the family of the Ubuyashiki house was short-lived was that Kibutsuji became a demon.
“Because I got a monster like you out of the clan.” “My clan was cursed.”
Meanwhile, the priest advised that “a demon is coming out of the same bloodline,” “pour your heart and soul to defeat that person,” and “then the clan will never cease.” Since then, the Ubuyashiki house It seems that a long battle with the Kibutsuji has begun for more than 1000 years.
Summary：
1：Kibutsuji was originally a human being and was of the same kinship as the Ubuyashiki house clan.
2：The Ubuyashiki clan was cursed when Kibutsuji became a demon and became short-lived.
3：The Ubuyashiki clan has survived the clan by devoting their heart and soul to defeating Kibutsuji.