L'Arc Berg Sickle, the Scythe Hero, hails from a world endangered by the Waves of Catastrophe. Though king of the small country that summoned Kizuna Kazayama, the Hunting Hero, he favors adventuring over royal duties. Wielding the Vassal Scythe grants him enhanced combat abilities, specializing in close-range battles and wind-based techniques, synergizing effectively with Therese Alexandrite's elemental magic. He first appears anonymously during the Cal Mira Island arc, befriending Naofumi Iwatani while level-grinding. Skeptical of Naofumi being the Shield Hero due to conflicting rumors, he initially believes Mald holds the title. When the Wave strikes, L'Arc reveals his mission to kill the Four Cardinal Heroes to save his world, confronting Naofumi's party directly. Despite aid from Glass and Therese, he fails to defeat them. His role transforms from adversary to ally during the Spirit Tortoise crisis after the Vassal Weapon wielder Kyo Ethnina betrays their world. Compelled by his weapon to stop Kyo, L'Arc forms an uneasy alliance with Naofumi. They cooperate to defeat Kyo, with L'Arc later aiding Naofumi's group after being imprisoned within Kyo's world and escaping thanks to Raphtalia. This collaboration extends to peace talks between their worlds. Later, his kingdom faces turmoil when Vanguards of the Waves steal his Vassal Scythe and kidnap Kizuna. With Ethnobalt's aid, Naofumi arrives as reinforcements, enabling L'Arc to reclaim his weapon and assist in Kizuna's rescue. He also defends his nation against attacks led by Mald and others during a two-pronged assault, successfully repelling them before reinforcements appear. Personality-wise, L'Arc displays a carefree, older-brother-like attitude, often using nicknames such as "kiddo." He possesses strong morals, avoiding harm to bystanders, and demonstrates sharp judgment, recognizing Mald's deceit. Despite playful and occasionally perverse tendencies, he commands respect as a charismatic leader. He harbors romantic feelings for Therese Alexandrite, showing jealousy over her admiration for Naofumi's crafting skills, and forms a comradely bond with Motoyasu Kitamura after shared misadventures.