Item from Demon Slayer by Koyoharu Gotouge
A specially crafted wooden box that Tanjiro carries on his back — Nezuko's portable coffin and daylight shelter, treated with rock lacquer to block sunlight.
The box was crafted by Urokodaki specifically to protect Nezuko during daylight travel. It's lined with cloud-patterned fabric (Urokodaki's signature) and treated to be as lightproof as possible. Nezuko shrinks herself small enough to fit inside and sleeps during the day, recovering strength without consuming humans. The box is simultaneously the most practical and most symbolic object in the series. Tanjiro carries his demon sister on his back through every battle, every mission, every mile of travel. When Sanemi stabbed the box to provoke Nezuko, he was attacking the physical manifestation of Tanjiro's promise to protect her. The box survived that test. So did Nezuko.
A rectangular wooden box approximately the size of a large backpack, worn on Tanjiro's back with rope straps. The wood is dark, treated with multiple layers of rock lacquer for sun protection. Metal fittings reinforce the corners. A sliding door panel allows Nezuko to emerge quickly. Despite its solid construction, Tanjiro carries it at full combat speed — a testament to both his strength and what the box represents.
Also known as: Tanjiro's Box, The Wooden Box, Demon Box