For the first time in the 5 years of his own existence, Danzel tried to teach one of his spells to someone else. That someone else being Shiro, a particular genius of magic.
He thought that someone like her would easily be able to understand a spell-like [Sense of the Damned]. But once he started teaching her, he found that she couldn't fully understand the concept of dead mana.
That's when Danzel that he had to start with the basics with her.
He tried to explain to her how to create dead mana and manipulate it.
Her first attempts were frustrating to watch, as instead of dead mana, she would create dark mana with only a tiny amount of actual dead mana. Which lead to some confusion for Shiro as dead mana and dark mana had little visual difference from each other.
For Danzel it was particularly annoying in watching attempt after attempt of her failing, which further dispirited Shiro, who was always very understanding of magic and mana.
