User blog comment:Caudyr/Abilities List From the Author + Translation of Abilities as I go Through the Story.../@comment-24863069-20151112143601/@comment-124.83.16.225-20151113035645

Rou actually did summon Ogres with his ability; he pitted them against Scarface, to see how strong a Black Undead Knight was. I'd say that was how he got the exact number for how many Ogres a Black Undead Knight could take on.

Rou also summoned a Black Orc and Black Minotaur during his party's foray into the Flame Mountain Dungeon. They were guards for them while they slept, then breakfast when they woke up.

Kobolds were mentioned to be Demonkin, if I recall correctly. I can no longer remember exactly when I read this, but I made a point of mentally categorizing them in the same species. It's not that farfetched, is it? Vampires and ghouls are Demonkin too, along with the Monkey Men.