Warding Mask

Warding Masks (の) are kitsune masks made of wood that Sakonji personally hand-carves for his students to protect them from harm.

Overview
Sakonji possesses a remarkable talent for crafting wooden masks. As he has a particular fondness for foxes, his creations exclusively take the form of kitsune masks, intricately carved to resemble the face of a fox.

Before their entry into the Final Selection, Sakonji presents the masks as precious gifts to his beloved students. These masks hold more than mere aesthetics, as Sakonji imbues them with a protective spell, intended to shield the wearers from harm. However, the efficacy of this enchantment comes into question, as all thirteen of Sakonji's previous students who wore the masks tragically met their demise at the hands of the Hand Demon. The masks have inadvertently become a means for the demon to identify Sakonji's students, drawing his vengeful wrath upon them due to the deep-seated animosity he holds towards Sakonji for imprisoning him on Mount Fujikasane.

During the Final Selection, Sakonji's students wear the masks on the left side of their heads, secured by a piece of rope and leaving their faces fully exposed. After their death, some of the students used the mask to conceal their entire face when their souls appear before Tanjiro, symbolizing their unwavering connection to their master even in death.

Final Selection Arc
During Tanjiro's struggle to split the boulder assigned to him by Sakonji, Sabito suddenly appeared atop the boulder, wearing a mysterious mask that covered his entire face. Tanjiro was taken aback by Sabito's unexpected presence and the sight of the unique mask. Sabito leapt down from the boulder and initiated an assault on Tanjiro, urging him to fight back. Overwhelmed, Tanjiro was quickly knocked out cold. When he regained his senses, he found himself confronted by Makomo, who was also wearing a kitsune mask. Makomo proceeded to teach Tanjiro the essence of Total Concentration Breathing. Under her guidance, Tanjiro engaged in a six-month-long battle against Sabito. Eventually, he successfully sliced Sabito's mask in half with his blade, revealing Sabito's friendly countenance beneath. Mirroring the fate of Sabito's mask, the boulder before Tanjiro was also split in half.

Sakonji grants Tanjiro the permission to partake in the Final Selection. As a token of protection, Sakonji presents Tanjiro with a kitsune mask, akin to the ones worn by Sabito and Makomo. He explains that it is a "warding mask" imbued with a powerful spell. Its purpose is to safeguard Tanjiro from harm and invoke the mountain god's protection, ensuring his safe return from the daunting challenges of the Final Selection.

During the Final Selection, Tanjiro dons the warding mask crafted by Sakonji. Instantly recognizing the mask, the Hand Demon taunts Tanjiro, boasting about devouring thirteen of Sakonji's students and ridiculing the mask's supposed protective abilities. He even specifically praises Sabito's strength and Makomo's agility among Sakonji's students. After a grueling battle, Tanjiro successfully beheads the Hand Demon. However, during the fight, Tanjiro's mask shatters, breaking the spell and nullifying its protective properties, potentially averting a disastrous outcome. As a result, Tanjiro survives the encounter. The spirits of all of Sakonji's students, adorned with the warding masks, appear before Tanjiro, finally finding peace and solace.

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 Okami also called "O-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.