FYI, this conflict seems to be a continuation of the war that has started since Demon Lord Dokfel, the Demon Lord before Derkila (c. 358)
Chronologically,
Dokfel asked Mephisto to choose between Alvro and Kushinashi. These are not just passing name, i suspect that Kushinasi is a Levi while Alvro...
I think you're onto something. Kirio's first plan was infiltrating the school. Only when his plan was foiled, they chooses an indirect method.
Remember Orobas Coco during the Harvest Festival? He was manipulated by Ocho, Baal's underling.
And when he was found out, they send Atori and Shiida...