Rudeus Greyrat began as a 34-year-old Japanese NEET reincarnated into a fantasy world after perishing in a truck accident while rescuing teenagers. His previous life saw him become a reclusive shut-in following severe high school bullying involving public humiliation and physical abuse. After his parents' death, siblings disowned him for missing their funeral, rendering him homeless shortly before his demise. Reborn with intact memories, he discarded his former identity and resolved to live purposefully as Rudeus Greyrat. Physically, he stands around 175 cm with light brown hair, green eyes, and a mole under his left eye. Kishirika Kishirisu later replaced his eyes with demonic counterparts, creating heterochromia: a Foresight Eye in his right socket for limited future vision and a Clairvoyant Eye in his left for long-distance sight. Intense battles occasionally drain his mana, bleaching his hair temporarily before it regrows normally. He initially wore simple gray adventurer's robes but adopted refined clothing in adulthood. His personality merges both lifetimes, marked by extreme self-awareness and humility to avoid past arrogance. Fiercely loyal to loved ones, he reacts aggressively to threats against them yet prefers diplomacy over killing. Childhood trauma induced agoraphobia, overcome through Roxy Migurdia's mentorship. His previous life's perversion persists as an obsession with women—especially large breasts—though he remains exclusively faithful to his wives. Neurotic tendencies include strict anti-rat protocols after Hitogami used one to endanger Roxy. Magically, he possesses mana reserves exceeding Laplace's, amplified by early training and a strong Laplace factor. He mastered voiceless incantation for near-instant spellcasting in all magic except healing. His ranks include Water Emperor and Saint-tier in fire, earth, wind, healing, and detoxification magic. He innovated spells like "Quagmire" (water-earth fusion), "Electric" (weakened lightning), and "Nuclear Explosion" (god-tier fire-air fusion). Unable to generate traditional battle aura, he learned Saint Dragon Battle Aura from Orsted, blending martial arts with magic. His tactical genius leverages environmental manipulation and psychological strategy. Key events include Roxy curing his agoraphobia at age three; tutoring his cousin Eris Boreas; surviving a continent-wide teleportation disaster that stranded him with Eris on the Demon Continent; founding the "Dead End" party with Eris and Ruijerd Superdia to redeem demons; gaining demon eyes from Kishirika; and reuniting conflictually with his father Paul. Eris's departure after their first sexual encounter triggered severe depression and erectile dysfunction. Later, he enrolled at Ranoa Magic University, reunited with Sylphiette, married her and Roxy, then reconciled with Eris as his third wife. Allied with Orsted against Hitogami, he lost his left hand rescuing his mother Zenith before Orsted restored it. He founded a religion deifying his three wives and fathered six children: Lucy, Lara, Sieghart, Lily, Christina, and Ars. He died naturally at 74, with descendants continuing his conflict against Hitogami.