How did I, an Onmyoji, become the Lord of Yokai?

Raised by a yokai, Asahi Shimizu has always carried one dream: to see humans and monsters set aside their age-old prejudices and coexist in peace. Driven by that vision, he trained relentlessly and studied with unwavering dedication. Upon graduating from the Yin-Yang Bureau, he threw himself into resolving conflicts on both sides—mediating disputes, mending rifts, and standing as a bridge between two worlds. Twenty years passed. Now, looking upon the oni queen Takiyasha-hime, the great demon of Mount Ōe, Ibuki-dōji, the daughter of Mount Suzuka, Suzuka Gozen, and the master of a hundred tales, Aoandon—all gathered at his side—he could not help but sigh with quiet fulfillment. His dream had finally come true. Yet somewhere along the way, his fellow onmyoji had stopped seeing him as a mere mediator. They began to whisper a different title—one that made him pause. Why, exactly, were they calling him the Lord of Yokai?