Sesshoumaru is a powerful and cold Inu daiyoukai (great dog demon).
He is the half-brother of Inuyasha, having the same father, the powerful
Inu no Taishou.
Although Sesshomaru has inherited his father's Tenseiga, which can
bring 100 people back to life with a single swing, he covets Inuyasha's
inheritance, Tetsusaiga (Tessaiga). However, a barrier was cast around
Tetsusaiga so that full youkai cannot wield it without burning their
flesh. Even knowing that he cannot touch the sword, Sesshomaru still
desires to take it from Inuyasha.
Sesshoumaru is followed by his retainer, an imp-like youkai with a
small beak named Jaken, and later by a human orphan named Rin, whom
Sesshomaru brought back to life using Tenseiga. He is also followed
by a two-headed dragon that Rin named Ah-Un. Ah-un is Rin and Jaken's
main form of transportation when Sesshomaru takes flight or when they
need to cover long distances quickly.