Demon Slayer: Kimetsu no Yaiba Episode 40: Transformation

Tanjiro struggles to keep up with Daki while Nezuko’s demon power surges to an alarming level, allowing her to overpower Daki and push the fight through the district. The battle escalates further when Tanjiro desperately tries to stop Nezuko from losing control, and the Sound Hashira arrives and appears to finish Daki off — only for a new demon to emerge, revealing that the situation is far more dangerous than it first seemed.

Nezuko begins the episode in an intensified demonic state, with her body changing dramatically as she grows stronger and more feral in the fight against Daki. Her regeneration becomes so impressive that she can continue fighting even after severe damage, and she uses a fiery blood technique that burns Daki. As the fight spreads into nearby areas, Nezuko’s escalating bloodlust becomes a threat to bystanders, and Tanjiro notices that she is beginning to lose her grip on herself.

Tanjiro intervenes to stop Nezuko from attacking innocent people, using physical restraint and pleading with her until she starts to calm down. Her violent state is finally interrupted, and she returns to a more familiar, smaller form before falling asleep again. This lets the battle refocus on Daki, who is still standing and still dangerous.

At that point, Tengen Uzui arrives and cuts off Daki’s head in a single attack, briefly seeming to end the fight. However, Daki does not die, and a second demon emerges from her body, revealing that the Upper Six threat is not just one opponent. The newly appeared demon heals Daki and takes over the battle with sickles and blood-based attacks, forcing Tengen into a much harder fight than before.

The episode ends with the conflict still unresolved, as Tengen realizes he is facing a far more dangerous enemy than Daki alone, while Tanjiro has just managed to restrain Nezuko in time.