Bosse, an adventurer of unknown origin driven by obsession for strength, traveled widely seeking challenges. His journey brought him to the Houma Kingdom, a land of powerful mages, where he dueled Miranjo's father. Though Bosse narrowly won, he suffered grievous injuries. Nursed back to health by Miranjo's mother, he developed deep affection for young Miranjo and allied with Houma against the Gods. When the Gyakuza Kingdom betrayed Houma, slaughtering most of its people, Bosse returned to find Miranjo tortured and mutilated. He retaliated by destroying a Gyakuza village, using their remains to restore her through a physician. After restoring Miranjo, Bosse wandered with her. Facing his natural limits, he accepted her suggestion to seek demonic power. The demon offered enhanced strength stolen from a relative, leading Bosse to bargain for his future son's might. Miranjo directed him to court the giantess adventurer Sheena. Though initially for the bargain, Bosse grew to love her. When Sheena gave birth to Bojji, the demon transferred the child's future strength to Bosse, making him the world's strongest being. Witnessing his newborn son, Bosse felt profound guilt. In penance, he founded the Bosse Kingdom on Bojji's birthplace, vowing to protect his family. As king, Bosse ranked 7th in the global Ranking of Kings system, evaluated on kingdom prosperity, personal strength, and warrior quality. His unparalleled power—from giant heritage and stolen strength—earned him the title of world's strongest man. He crushed wooden clubs into diamonds and destroyed stone golems in single strikes during rankings. Bosse appointed the "Big Four" advisors—Apeas as King's Spear, Dorshe as Queen's Shield, Domas as Swordmaster, and Bebin as Snake Master—tasking them with protecting the royal family and managing the kingdom. Years after founding the kingdom, Miranjo staged a coup using Gigantes, resulting in Sheena's death shielding Bojji from arrows. Miranjo was believed killed. Bosse's whereabouts during the coup were unclear, though he later slew the god Chabi-shin. Roughly a decade into his rule, Bosse succumbed to a mysterious illness, dying surrounded by court. The demon appeared, hinting at the bargain's consequences. Miranjo, surviving spectrally in a magic mirror, resurrected Bosse by transferring his soul into his second son Daida's body. As Daida, Bosse became an enigmatic court presence, aware of Miranjo's manipulations but avoiding confrontation due to lingering obligation. He battled the immortal Ouken, crushing him repeatedly before trapping him in stone. Bosse then confronted Bojji, who sought to reclaim Daida's body. Despite overwhelming strength, Bojji dodged all attacks and destroyed Bosse's club. Impressed by Bojji's growth, Bosse relinquished the fight. Finally, he persuaded Miranjo to depart the mortal world with him, their souls fading into the ether. Bosse's relationships centered on guilt and obligation. He felt immense remorse for stealing Bojji's strength and founded the kingdom to atone, ensuring Bojji's safety. On his deathbed, he confessed deep affection for Bojji, noting his resemblance to Sheena. With Miranjo, he acted as surrogate father, driven by guilt over her past, yet failed to curb her jealousy toward his family. Physically, Bosse was a towering giant with shaggy brown hair, a beard, prominent scars, and a stern face, later inhabiting Daida's smaller form after resurrection.