maou, {makai no shihaisha ni shite} {subete wo gyuujiru} akuma no ou 魔王悪魔の支配者にしてすべてを牛耳る悪魔の王 Demon-king: [he] {is the lord of the demon world, and} the king of demons [that] {rules over everything}.
Here, we're saying the maou is the makai no shihaisha on top of also being subete wo gyuujiru akuma no ou.
