The first scene in Kimetsu no Yaiba is a crying Tanjiro running down a snowy forest with the unconscious Nezuko on his back. We don’t know what happened, much less who they are, but we can see Tanjiro’s desperation as he cries and wonders why his family was struck by misfortune. And after a few flashbacks that tell us exactly how his life was and how it was destroyed, suddenly Nezuko opens her eyes… and they’re no longer human.

The sweet girl we saw minutes before is now a monster that immediately attacks Tanjiro with the very clear intent to eat him. It's only thanks to his fast reflexes that he manages to put his ax between her teeth and, just when we think one of the two will die, we see that Nezuko is crying. It’s impossible not to cry with her and her brother since we know neither deserved the horrors that will follow.

As he was training to become a demon slayer, Tanjiro hit a plateau where he was unable to advance. Abandoned by his teacher Urokodaki, he is confronted by two fighters, the strong Sabito who pushes him to really understand Urokodaki’s teachings, and the frail Makomo who explains to him what’s behind said teachings.

It’s not until he reaches the Final Selection that Tanjiro learns that both Sabito and Makomo are ghosts: They were killed by a Hand Demon during their Final Selection exam precisely because they were Urokodaki’s students. We see how they died, tortured and scared. It's a heartbreaking scene that reminds us of the stakes that Tanjiro will face in the future.

Thanks to his keen sense of smell, it’s quite early on when Tanjiro finds the demon that turned his sister, a creature known as Muzan Kibutsuji. We know their encounter will be short, as it’s only episode 7, but the way it’s cut short, just after Tanjiro touches Muzan’s shoulder in a busy street in Tokyo is what makes it heartbreaking.

See, Muzan has a young human child with him, who calls him Papa. And as Tanjiro is reeling from that revelation, he finds out that Muzan also has a wife. Both the child and the woman are humans, and Tanjiro doesn’t know if they know the truth about Muzan, which is improbable. And as he’s still trying to understand, Muzan casually turns a passerby into a demon, just to distract the Slayer. So many lives destroyed in just a second and for no reason. It’s hard not to share Tanjiro’s tears.

While the whole spider demon clan is pretty tragic when we realize that they were being forced to play house with Rui and were tortured, punished, and killed if they made the young-looking demon angry, we can’t really feel that sorry for them since they were demons and had eaten a couple dozen humans each before arriving at spider mountain. But when Rui himself dies, we get a glimpse of his past and the human he used to be before meeting Muzan and it’s impossible not to feel bad for him.

Rui was just a sickly boy whose parents made a deal with Muzan, who was pretending to be a doctor at the time, to give him a stronger body. When they realized that Rui was killing humans, his parents were ready to kill him and then die with him, but Rui killed them. And if that wasn’t tragic enough, when Rui finally dies at the Slayer’s hands, their souls were waiting for him, ready to accompany Rui to hell. Even Tanjiro cries at the grief Rui gives out.

Some may consider that we’re stretching the concept of “scene” here, but as we see it every episode, we figure it counts. It’s really heartbreaking as it starts with beautiful scenes of the Kamado family’s life before the fateful night that destroyed them all. We even see Tanjiro’s father dance, even if we don’t get the full meaning of that little snippet until much later into the series. It's a tragic memento of what could have been if their lives hadn't been destroyed by Muzan’s cruelty. And as we learn that the souls of the dead watch over their families, we can imagine Tanjiro and Nezuko’s siblings and parents crying as their relatives suffer.