Menomaru is a demon from China who attempts to invade Japan. He is opposed by Inuyasha's fathe, but returns two-hundred years later to battle once more with Inuyasha.
He doesn't appear in the manga or the anime, but is the main foe in InuYasha: Toki wo Koeru Omoi.
Two-hundred years after Inuyasha's father defeated Menomaru's father Hyoga, he is revived by the power of the Shikon shard when the jewel shattered.