After fending off two Demons at the start of Final Selection, Tanjiro notices a rotten smell and the screaming voice of a boy fleeing in fear. Tanjiro glances is over and is horrified to notice a large, green, morphed Demon with hands covering its entire body. The Demon swallows a dead boy whole and grows stronger from devouring him.
The Hand Demon launches its hands at the fleeing boy and pulls him in. Before the Demon eats him whole, Tanjiro works up the nerve to leap into action. He cuts the arms off using Water Breathing: Water Wheel. Despite being wounded, the Demon seems happy to see another "fox cub" and asks what the year of Meiji is. After Tanjiro tells him it is the Taisho Period, the Demon goes crazy and curses Sakonji Urokodaki for training him on the mountain forty-seven years ago.
Tanjiro is surprised to learn the Demon knows of Sakonji. The Demon was trapped there by Sakonji in the past and he's been feeding on all his student's as revenge. He can tell them apart from other contestants because of the warding masks he crafts for his children. The Demon has survived in this wisteria prison by eating over fifty candidates during the selections, including thirteen of Sakonji's pupils.
It turns out that Sabito and Makomo were the strongest among the students slain by this Demon. He starts explaining how he killed them and hopes Sakonji feels responsible. This throws Tanjiro into a rage and he rushes at his enemy in a fit of revenge. The Demon sends several extended arms flying at the "fox cub", who bares his fangs and slices the arms apart with his sword.
All of Urokodaki's children watch over Tanjiro. Sabito reminds him to calm down and even out his breathing. He wants Tanjiro to forget about them for now and focus on winning this fight. Enraged, Tanjiro leaps for the Demon's head but is punched away and crashes into a tree. The boy falls injured with his mask broken and bleeding from the head.
The boy Tanjiro saves flees the area and leaves him for dead. However, the voice of another familiar soul calls out to his big brother and wakes Tanjiro in time before the Demon ensnares him. Tanjiro back flips out of the way and the Demon unleashes a barrage of extended arms. The swordsman in training cuts away at the arms until he's forced to retreat.
The Demon claims Tanjiro can't win just by slicing away his arms. He taunts the boy by saying not even Sabito was able to slice his neck. Sakonji's latest student cuts off another arm and stands off with the Demon. He knows he can't lose and must bring down this morphed Demon in this decisive battle. Tanjiro charges toward the Demon, cutting off three more arms before noticing the Demon's scent coming from below him.
Four hidden arms appear from the ground but Tanjiro jumps out of the way in time, surprising his opponent. The Demon tries to capitalize and grab Tanjiro while he's in mid-air. Meanwhile, Makomo asks Sabito if Tanjiro can possibly win. Sabito claims he can't predict the outcome, but he reminds Makomo that Tanjiro is the man who sliced the largest, toughest boulder of all Sakonji's students.
Tanjiro deflects the hand with his rock-hard head and flips on to the Demon's giant outstretched arm. The Demon spawns smaller arms and tries to stop Tanjiro, but he counterattacks with Total Concentration Water Breathing and swiftly slashes the arms apart as he flies through his enemy's defenses. Tanjiro manages to get close to the Demon's head with a leaping strike. The Hand Demon believes his neck is too tough for his opponent to cut and plans to crush his head after the sword fails. However, Tanjiro reveals the opening thread and decapitates the Demon with Water Breathing: Water Surface Slash.
The manner of the Hand Demon's defeat reminds it of the previous loss at the hands of Sakonji. The Demon recalls feeding on some humans before being discovered and captured by Sakonji in his prime.
Tanjiro beheads the Demon and its morphed body disintegrates into nothing. The Demon regrets that the face of a Demon Slayer will be the last thing he ever sees. He's surprised to notice Tanjiro's sad expression despite his victory. It reminds him of his past life as a human, when he accidentally killed his beloved brother before descending into darkness.
Tanjiro recognizes the sad scent and prays that God won't reincarnate this man as a Demon. The spirits of Sakonji's children watching over him appear. Tanjiro tells them he won and asks their souls to rest in peace at last. Sabito, Makomo in the other disappear, but their will lives on inside Tanjiro. If he had died, his soul would've returned to Sagiri Mountain as well.