TV-Series
Description
Willem Kmetsch, born over five centuries ago as a human in the city of Gomag, spent his youth in an orphanage. He became the primary caretaker for the other children, including Almaria Duffner who saw him as a father figure and called him "Pops." His mentor was Nils Didek Foreigner, the former 18th Legal Brave, who trained Willem alongside Lillia Asplay and Souwong Kandel. Despite this rigorous training, Willem lacked the innate talent to become a full Regal Brave, instead achieving the rank of Quasi Brave within the Church of Holy Light. He earned the moniker "Black Agate Swordmaster" from comrades, though he possessed genuine skill in tuning Carillons (later known as Dug Weapons).

In the final battle against the Poteau, Willem confronted the immortal Ebon Candle. He defeated his foe by wielding multiple Carillons and invoking seven forbidden curses, but suffered a severe backlash that petrified his body approximately one year before humanity's extinction by the Beasts. He remained frozen for 525 years until an excavation team led by Nygglatho and Grick Graycrack discovered him. Depetrified, Willem awoke to a world devoid of humans, experiencing profound despair and trauma upon learning his race was extinct. His body retained extensive damage from the curses, including shattered bones, damaged organs, and compromised mobility, making prolonged physical exertion or use of his abilities potentially fatal.

To repay medical debts, Willem accepted work under Grick, who educated him about the floating islands' society, politics, and prejudices against "Disfeatured" beings like himself. After over a year of odd jobs, Grick arranged for him to become a military caretaker at a warehouse housing "Leprechauns"—young girls who wielded Dug Weapons against the Beasts. Initially reluctant due to his aversion to military involvement, Willem adapted using his orphanage experience, preparing meals, providing emotional support, and maintaining the girls' weapons. His relationship with the eldest Leprechaun, Chtholly Nota Seniorious, evolved from mutual wariness to deep romantic attachment, culminating in an engagement. He formed paternal bonds with others, including Nephren Ruq Insania, who frequently sought his company, and Ithea Myse Valgulious, who teased him about his interactions.

Willem uncovered disturbing truths: the Leprechauns were artificial beings created from deceased children's souls, designed for sacrificial battle, and the Beasts were mutated former humans. This intensified his resolve to protect the girls. When Chtholly began suffering mental degradation due to the soul of Elq Hrqstn overwriting her consciousness, Willem sought a cure. Despite his efforts, Chtholly sacrificed herself to save him during a Beast attack, using her powers until her mind collapsed. Subsequently, Willem and Nephren were drawn into a dream world created by the Beast Chanteur, where Willem learned the full history of humanity's fall. He killed Almaria (possessed by Chanteur), releasing the Beast, which then split and infected both him and Nephren.

As Willem transformed into the Beast Shiantor, his master Nils intervened, cursing him to seal his memories and suppress the Beast within. He lived amnesiac with the resurrected Elq Hrqstn until a Beast attack on the floating islands restored his memories. In a berserk state, he destroyed corrupted weapons but lost control and battled the Leprechauns. He was ultimately killed by Rhantolk Ytri Historia and activated a hex to ensure his permanent death. Nils later offered to transform him into a Visitor to leave the planet, but Willem refused. Ten years later, efforts by Elq and Nephren removed Seniorious's curse and revived him. He reunited with Nygglatho and a blue-haired girl named Ryehl, implied to be Chtholly's reincarnation.

Willem exhibited a complex personality shaped by loss and duty. Initially jaded and burdened by survivor's guilt, he regained purpose through caring for the Leprechauns. He displayed paternal protectiveness, snarky humor, and deep-seated trauma over his failures. Despite physical limitations, he utilized Venenum—a life-force energy—to enhance his strength and speed in short bursts, risking fatal strain. His combat style relied on tactical ingenuity honed from his Quasi Brave days, allowing him to confront threats unarmed or with basic weapons.