As Tanjiro and Giyu continue through the castle, the former nearly falls through an opened floor, commenting the building is seemingly trying to seperate the two. While wondering how long can Tamayo withstand Muzan and unsure of their location, a Kasugai Crow announces that Shinobu Kocho has encountered and was killed by Upper Rank Two. While Tanjiro holds back tears remembering her, Giyu notices the crow has a piece of paper on its neck.
In the new Demon Slayer's headquarters, Kiriya Ubuyashiki has become the new head of the Demon Slayer as the only remaining male, doing so at the age of 8; he is supported by his sisters Kuina and Kanata. Despite the deaths of his parents and two elder sisters, he willingly hasn't grieved them in order to focus on the mission. Kuina and Kanata also hold back their emotions to aid him. Their father, with his short lifespan, was strict, raising them quickly into adults as quickly as he could. Their elder sisters Hinaka and Nichika had never left their father or mother's side, their mother was also kind but strict in raising them.
The three each have one of Yushiro's talisman, helping them map out the Infinity Castle. Kiriya notices the lacking information they need and suggests telling the crows to spread as many 'eyes' as they can, even one can aid well. Kuina deduces Muzan hasn't from his place and instructs Kiriya into guiding them north to face him. She mentions the only Demon Slayers currently facing Upper Moon Demons are Kanao and Zenitsu, the latter now facing Upper Rank Six.
Zenitsu and Kaigaku face off, Kaigaku mocking Zenitsu as puny and weak, scoffing at his status as a Hashira since he is only able to do one form. Zenitsu retaliates by mentioning how happy his former superior seems as the bottom Upper Rank, especially the fact that he is nothing more but a replacement to fill the slot of the previous Upper Moon, Kaigaku stunned at his barbed comment. Zenitsu questions how could he have turned into a demon, when Kaigaku tries to answer, Zenitsu cuts him off and continues. "Why would someone poised to acquire Thunder Breathing become a demon?". Zenitsu angrily yells that Jigoro Kuwajima had commited seppuku by himself upon hearing what Kaigaku has done. Someone was meant to assist him at the act but instead, he died agonized and alone, all because a user of the Thunder Breathing became a demon.
Kaigaku scoffs at the news and asks if he's meant to be sad or repent, unapologetically refusing to care. He declares he will always sticks to those who value him. He states he is glad Jigoro died a painful death, angered that all his efforts to please him never led to being named his successor, and insults him further by scoffing at his idea of sharing the successorship with "dirt" and calling the former Hashira senile. Zenitsu furiously tells him if he was dirt, Kaigaku was garbage, since he can only use the first breath and Kaigaku never manage to learn it, commenting Jigoro only died miserable because he wasn't lucky enough to have a true successor.
Kaigaku angrily tells him not to put the likes of himself with him and unleashes the Thunder Breathing, Fourth Form: Distant Thunder, sending lightning at the demon slayer. However, Zenitsu has already avoided the attack and slashed the demon's neck, mocking him, "You're too slow, you filth". Kaigaku is stunned his opponent has already slice him and comments he seems like a completely different person.
Characters in Order of Appearance
- Kiriya Ubuyashiki
- Kuina Ubuyashiki
- Kanata Ubuyashiki
- Tanjiro Kamado
- Giyu Tomioka
- Shinobu Kocho (Flashback)
- Kanao Tsuyuri (Flashback)
- Aoi Kanzaki (Flashback)
- Sumi Nakahara (Flashback)
- Kiyo Terauchi (Flashback)
- Naho Takada (Flashback)
- Hinaki Ubuyashiki (Flashback)
- Nichika Ubuyashiki (Flashback)
- Kagaya Ubuyashiki (Flashback)
- Amane Ubuyashiki (Flashback)
- Zenitsu Agatsuma
- Jigoro Kuwajima (Flashback)