Dairoku Tenmaou (ダイロクテンマオウ, Dairokuten Maō)?, also known as Rokuten Maou (ロクテンマオウ, Rokuten Maō)? and Demon King, is a recurring demon in the series.
Within the Gohonzon, a revered mandala in Japanese Buddhism, the "Dai-roku-ten-maou" (第六天魔王) or the "Demon King of the Sixth Heaven" symbolizes the lust for power and the desires to attain worldly goals. As the demon king with a great number of minions under his wing, the Maou works to tempt Buddhists from practicing the teachings of Buddha. The "Sixth Heaven", also known as Takejizaiten, the Japanese translation of the Sanskrit name Paranirmitavasavarti, is the realm where the demon king resides, thus he himself is also known as Takejizaiten or Takejizaitenjin. He is ultimately derived from the evil being Mara of source Buddhist lore and the adaptation of Mara into Japanese Buddhism.
This title is also referring to Oda Nobunaga, a 16th Century warlord known for his eccentric personality and cruelty in battle, who self-proclaimed to be this particular title. Thus, the demon model in Innocent Sin is based on the warlord himself, and traces of the samurai look and the fiery texture around his armor (possibly referring to the Honnō-ji incident) is seen in Kanji's Ultimate Persona.