Warding Mask

Warding Masks (の) are masks made of wood that Sakonji Urokodaki hand-carves and gives to his students before they attend Final Selection. He casts a spell on them to help protect their wearers from harm.

Synopsis
When Tanjiro Kamado was unable to split the boulder that Sakonji tasked him to do, Sabito appeared on top of the boulder. Sabito was wearing a warding mask, covering his whole face, it was the first mask Tanjiro saw and he was stunned by Sabito's sudden and unexpected appearance. Sabito then leaps off the boulder and starts attacking Tanjiro, while commanding Tanjiro to attack him. After he knocks Tanjiro out cold, Tanjiro wakes up to the sight of Makomo, who is wearing another kitsune mask. After she teaches Tanjiro the essence of Total Concentration Breathing and he keeps battling Sabito with her guidance for half a year, he eventually manages to cut Sabito's mask in half using his blade, revealing Sabito's friendly face. The boulder in front of Tanjiro is also cut in half, like Sabito's mask.

Sakonji gives Tanjiro his blessing to participate in the selection and gives him a kitsune mask similar to the ones worn by Sabito and Makomo. Tanjiro accepts it, while Sakonji explains that it's a "warding mask" that he has charged it with a spell to protect him from harm. He wants the mountain god to protect Tanjiro from disasters and to have Tanjiro come back alive from the Final Selection.

During the Final Selection, Tanjiro wears the mask and the Hand Demon immediately recognizes it as one made by Sakonji. He taunts Tanjiro by saying he ate 13 of Sakonji's students and even laughs that the warding ability of the mask never worked. He describes Sabito as the strongest student he faced and Makomo as the most agile one. After a tough fight, Tanjiro successfully decapitated the Hand Demon. During the battle, Tanjiro's masks breaks, causing the spell to also be broken and it can be assumed that it was a substitute for disaster. Because of this, Tanjiro survived. The souls of all of Sakonji's students appear before Tanjiro, all of them wearing the warding mask made by Sakonji, finally able to rest.

Trivia

 * In Japanese folklore, Kitsune are beings that possess supernatural capabilities that increase as they get older and wiser. The kitsune is said to have been the messenger of Inari Ōkami also called "Ō-Inari", the kami of the mountains of the rice fields. As a messenger of the kami, it was said that kitsune would come down from the mountain in spring to protect the growth of rice, and return the mountain after seeing harvesting in autumn. From there, it has been praised as being a messenger of Inari to ward off evil spirits. Wearing a fox mask would thus protect people from harm.
 * Sakonji only made masks with the shape of a fox's face. It is apparently simply because he likes foxes.