Cramming
Rino cut to the chase. With his shadow army busy with the farm and shelter construction, he decided to ask his dark magic teacher to start the first class.
"I want to know the basics of dark magic," he told Kragami, who settled on the little stool because Rino was sitting on the mattress.
There really wasn't much in the hut, and this was the only abode in the farm they were in. He was slightly curious how Rino managed the rest of his undead army. Did he un-summon them when it was daytime?
Instead, he kept those questions to himself for now.
"What do you understand about dark magic?" Kragami asked. It was better to check Rino's progress than to assume this lich knew nothing.
Rino only listed the dark magic spells he knew and explained the theory of mana he recently discovered thanks to Noir's hint, although he did not reveal who he learned his magic from.