The Tetsusaiga (鉄砕牙) is a fictional sword, wielded by half-human, half-youkai (hanyou) Inuyasha. It was made from a fang of Inuyasha's and Sesshumaru's full-fledged youkai father. In its 'docile' form, the sword looks like a regular (and rather battered) katana. When weilded properly, it transforms into a weapon roughly the size of a car bumper, and has the power to slay 100 demons in one swing by striking the Wind Scar (Kaze no Kizu). It also has a greater power created from the convergence of multiple Wind Scars (Kaze no Kizu) from a powerful opponent, that is known as Bakuryuuha. It is sought by Sesshomaru because he is jealous that Inuyasha received the more powerful weapon from their father. Somehow its sheath can 'summon' the sword, and the Tetsusaiga itself has great magical power -- It acted of its own accord when Inuyasha had fallen unconscious during battle once. It also binds the powerful youkai blood that came from Inuyasha's father and can transform him (practically) into a full youkai. It also has the ability to absorb magical abilities from the blood of a creature that possesses them, for example, barrier shattering.