Folgen is the former Knight Leader of the Farmas Kingdom.
Folgen was seen as a dependable leader, and (a) trusted retainer that King Edomalis could depend on.
However, he also seemed to care little for fellow Otherworlders, seeing them as mere "materials" to strengthen himself using his Spearhead.
A hero with a long military history. He was summoned by Razen long ago, but had no curse restricting his soul; and, instead choose to become Razen's underling willingly, as a friend.
During Farmus' war against Tempest, Folgen led an army unit against the monster kingdom. He later welcomed Razen to his camp after he barely managed to escape from Geld with Shogo through teleportation. Upon learning of Kyoya and Kirara's death, he sarcastically lamented their passing. This angered Kyoya, which prompted Folgen to explain that he and his comrades were only ever meant to be used as "materials" for his Spearhead. He then helped restrain Kyouya so Razen could take over his body, to replace his elderly one.
When Rimuru began massacring Farmus' army to claim enough souls to complete his transformation into a true Demon Lord, Folgen and Razen went to King Edomalis' tent to ensure his safety. Upon confirming that the king was well, Folgen entered the battlefield to stop Rimuru. However, he ended up being easily killed with a single shot to the head by the latter's attack, causing his brain to leak out.
Spearhead: It allows the user to take the skills of fallen comrades within eyesight, with a limit. It also allows the user to some degree control subordinates.