Demon Slayer is a modern fantasy shonen series starring the kind protagonist Tanjiro Kamado, who is on a quest to somehow restore his beloved sister Nezuko's humanity after she was turned into a flesh-eating demon. Usually, it's Tanjiro who does the fighting as a trained demon slayer, but sometimes, Nezuko has his back.
Nezuko has proven herself as Tanjiro's best ally several times during his journey to slay Muzan. At times, she's an even better travel companion for him than Inosuke and Zenitsu. Tanjiro is highly fortunate to have her around. There are many scenes where Nezuko supports her brother, either directly or indirectly as his best ally.
10 When Nezuko Went To Sleep For Two Years
Nezuko aided her brother in remarkable ways, including being less of a burden. Nezuko would never be a troublesome burden on purpose, so she finds ways to be less problematic for Tanjiro. This includes the simple act of going to sleep.
Nezuko is starving as a demon, but refuses to actually harm anyone or eat flesh. So, she did both Tanjiro and herself a big favor by remaining asleep for two years while Tanjiro trained, which kept her demonic hunger in check. That allowed Tanjiro to focus on training.
9 When Nezuko Agreed To Stay In A Box
This was another case where Nezuko was a fine ally by being cooperative and less burdensome. Like all demons, Nezuko can't stand direct sunlight, and that would make it difficult for her to travel across Japan with Tanjiro. So, a solution was found.
Tanjiro acquired a wooden backpack, and Nezuko, being a cooperative travel companion, had no qualms about staying in there all day. She can even shrink into her cute "smol Nezuko" form to fit in there better, which made things even more convenient.
8 When Nezuko Helped Tanjiro Fight A Demon Early On
For the most part, Tanjiro doesn't expect his sister to fight demons directly, since he is the one who was trained and equipped for fighting demon-kind. Early in the series, though, Tanjiro wasn't ready to fight demons, and he was practically helpless when an ordinary demon attacked them.
Nezuko came to her brother's aid when she performed a powerful kick that took the demon's head right off and even if that wasn't the final blow, it still did a lot of good. The demon was unable to do any more harm until the sun rose and vaporized it.
7 Nezuko Helped Tanjiro Fight The Swamp Demon
Tanjiro's first real mission as a demon slayer involved visiting a town haunted by a teeth-grinding demon that was actually made up of three bodies. This demon could use swampy water to ambush people out of nowhere. Tanjiro had a tough time fighting him that night.
Fortunately for Tanjiro, Nezuko was ready and willing to join the fray, and she took the fight to her fellow demon without mercy. With her aid, Tanjiro was able to dispatch the swamp demon at last, saving his latest victim in the process.
6 When Nezuko Took On Susamaru
Tanjiro and Nezuko soon met the benevolent demon Tamayo and her assistant Yushiro, but then trouble arrived. Susamaru and the eye-based demon Yahaba launched an assault, and it was up to Tanjiro and Nezuko to fight them off.
Once again, Nezuko was a fine battle companion for Tanjiro, using every bit of her strength to fight back against Muzan's two minions. Despite suffering heavy injuries, Nezuko did all she could to kick away Temari's weaponized balls and destroy her. In the end, the Kamados won.
5 When Nezuko Used Her Blood Demon Art To Enhance Tanjiro's Sword
During the battle against the spider-themed Rui, Tanjiro was on the back foot. He was no match for the Lower Moon 5, and at one point, Nezuko got herself stuck on Rui's web – she couldn't directly help Tanjiro fight. But she did have another option, her blood demon art.
Nezuko used her art to add fire to Tanjiro's technique, and with this added firepower, Tanjiro dealt a major blow to Rui. This bought the Kamados some time until two members of the Hashira, Giyu and Shinobu, showed up to finish the job.
4 When Nezuko Resisted Her Hun
Tanjiro and his allies were later taken to the Hashiras' compound, where the Kamados received poor treatment. Tanjiro was viewed as a traitor for having a demon companion, and the wind Hashira, Sanemi, wanted to prove that Nezuko was nothing more than a man-eating beast.
Tanjiro could only watch as Sanemi tempted Nezuko with his blood, but Nezuko resisted with sheer willpower. This helped prove that the Kamados were trustworthy and loyal allies to the Hashira, and Tanjiro has his sister to thank.
3 When Nezuko Freed Tanjiro From Enmu's Dream
During the Mugen Train story arc, Nezuko came to her brother's aid once again, and no one saw it coming. The Lower Moon 1, Enmu, trapped Tanjiros' entire party in a convincing dream to assassinate them, but Nezuko refused to let her brother die.
Nezuko's blood art fire wasn't enough to wake Tanjiro up, but her efforts did help Tanjiro realize that he was in a dream. That gave him a chance to devise his own method for escaping the dream world and take the fight to Enmu.
2 When Nezuko Dominated Daki
Nezuko shocked everyone in the Entertainment District story arc when she went up against the mighty Upper Moon 6, Daki on her own. She unleashed a brand-new ability that made her much stronger, and she repeatedly pummelled Daki while also using her blood fire art.
This helped Tanjiro's squad temporarily defeat Daki, though when Gyutaro arrived to aid his demonic sister, things became dire again. Later, Tanjiro and his new ally Tengen Uzui would need Nezuko's aid to survive Gyutaro's poison.
1 When Nezuko Destroyed Gyutaro's Poison
Gyutaro and Daki were finally slain, but Gyutaro's poison was still in effect, and the exhausted, injured demon slayers couldn't do much about it. That was when Nezuko's blood demon art came in handy, since this fire can do more than burn demon flesh. It can destroy almost anything demon-related, including poisons.
Nezuko's blood art cured Tanjiro and Tengen of the poison, and Tengen's three kunoichi allies were amazed when the fire healed their husband rather than cremate him. Once again, Nezuko saved the day without expecting anything in return.