User blog comment:Hitsuji Mamoru/Servant Creation Room 2 : Guess of the Who/@comment-4802891-20170310114853/@comment-4802891-20170310132237

Yes, the "Demons" here are a bunch of youkai. "???" hides how they are... let's say "summoned".

About "Idleness", the Japanese name for the skill would be 徒然 (tedium), from the saying 徒然なるままに (having nothing to do). I choose "Idleness" because it fits more with what I am referencing.