Episode 29

Should Have Been (本当なら) is the 29th episode in the Kimetsu no Yaiba anime TV series, and the 3rd episode of its second season.

Plot
Enmu stands on the locomotive on the Mugen train and mutters to himself about lucky they are to die while sleeping. He tells of how humans are all the same, Demon Slayers or not, they are led by their heart; once it's gets destroyed, they're trapped in a sleep they can never awaken from again. He senses that Tanjiro Kamado continues to fall deeper into his slumber as he dreams he is reunited with his family.

As Zenitsu Agatsuma falls deeper into his sleep, he dreams he is in a peach tree forest, with Nezuko as his girlfriend and travelling with her. He carries her on his back when she claims cannot swim and they traverse the mountains with his Thunder Breathing as transport. Inosuke Hashibara dreams he is leading a cave expedition, accompanied by a rabbit Nezuko, squirrel "Ponjiro" and mouse "Chuitsu" as his underlings. They encounter the beast that is the Mugen train in the cave and proceed to charge ahead to attack it. Kyojuro Rengoku dreams he is at the Rengoku Estate and he sits before his father Shinjuro to tell him of his promotion into a Hashira. Shinjuro dismisses his news and calls it worthless, adding he believes that Kyojuro would never amount to anything, as does he. Kyojuro walks out and sees his brother Senjuro, who asks about their father's answer, believing maybe he could be acknowledged as well should he become a Hashira. Kyojuro mutters to himself about his father never acted as such in the past; he once help the mantle of Flame Hashira but unexpectedly quit. And he too was once enthusiastic about training him. Kyojuro refuses to dwell in this and instead encourages Senjuro that despite their father's lack of acknowledgement, he will continue to be proud and passionate. Senjuro tears up when his brother mentions he as him as moral support.

The four children tasked by Enmu manage to enter their dreams, enabled by a rope made of his Blood Demon Art. Enmu explains the dream world contains a border to the realm of the subconscious, and they can pass it once they enter the dream and locate its edge; instructing them to destroy their spiritual cores to kill them. The girl tasked with Kyojuro finds the edge and crosses the border with an awl made with Enmu's bone. As she traverses the unusually hot and fiery realm of the subconscious, she manages to locate his spiritual core. When she goes in to destroy it, Kyojuro suddenly grabs her throat whilst both are still unconscious, causing the girl in the realm to be crippled and unable to move; she becomes stunned and amazed at his incredible survival instincts despite being fully asleep.

Tanjiro plays with Rokuta while his mother Kie decides to make them rice crackers, making him happy. Takeo becomes annoyed and too wants rice crackers, causing Hanako and Shigeru to add that they themselves want some as well. Meanwhile, the boy tasked with Tanjiro has entered the dream and overhears the Kamados. Tanjiro chops down wood for a fire, but when he fills the basket and begins walking home, he mutters, "Nezuko, let's go". Suddenly confused at his words, he looks back at the cut logs. He returns home and enters the living room, before looking around and asking on Nezuko's whereabouts. Takeo answers she is went out to pick vegetables, causing him to grow worried since it's day. The concern confused his siblings, but before he can explain, Kie asks him to fetch water for a bath.

As he walks to the river, he tries to make sense of his unusual remarks. He unexpectedly sees Nezuko's box in the corner of his eye but it vanishes when he takes a closer look. Wondering if it was simple a tool box, he reaches the river and fills his buckets. Suddenly, he sees himself in the water's reflection; the mirrored Tanjiro pulls him in and tells him to wake up, claiming he is under attack. Suddenly, Tanjiro realizes he truly is still on the train and asleep. The reflection begs him to wake up and fight, causing him to return to his home. In the living room, Tanjiro is fully aware he is in a dream but is unable to see a way to awaken. On the train, Nezuko falls out her box and sees Tanjiro and company still unconscious. She sees Tanjiro whispering he needs to wake up and tries numerous ways to do so; before she grows frustrated and head-butts her brother to awaken him. Failing to do so and bleeding from the impact, she begins to cry and tearfully tries again, causing her Blood Demon Art to activate. In the dream, Tanjiro becomes engulfed in Nezuko's flames, to the confusion and fear of his siblings. He smells her blood and becomes covered in more fire, regaining his Demon Slayer uniform and Nichirin Blade. Takeo and Hanako ask if he is alright, to which Tanjiro answers that he needs to leave.