Otakemaru is a onigami an Oni who is so powerful that he is considered to be both a oni and a god. He is o alongside Shuten-Douji and Tamamo-no-Mae to among the three great evil yokai in all of japan but sometimes replaced by the ghost of Sutoku Tenno who is a tengu in some versions.
Otakemaru is often associated with Suzuka Gozen who appears as allies turned enemies.
In pop culture
Otakemaru appears in the Fate franchise in side materials usually in flashbacks.
Otakemaru appears in the game Onmyoji as a boss.
Otakemaru later appears in Nioh 2 as the main antagonist of the game.