Seeing Hirschur's facial expressions in the manga is so peak. The artist is certainly living up to the standard set by their colleagues for (Roze)myne faces. Brunhilde's eyebrows are super funny with how expressive they are.
That's unfortunate for the author. Editors do so much to enable an author's success that if the author actually had one, it would have been a failure on the editor's part to support them.
Ashimitsu mentioned having test subjects. My assumption is he took a page out of history he learned while living in the modern world and developed drugs to put prisoners and the like into a beserker rage