Ten thousand years ago, the Supreme of the Human Race suddenly disappeared, leading to the decline of humanity and reducing them to blood food kept in captivity by the ten thousand clans. Delivery driver Su Xiao transmigrates to become a slave of the pig clan, awakening the Ten Thousand Clans Catalog system, where devouring the ten thousand clans allows him to acquire their talents and grow stronger. Risking his life, he saves Meng Jin and the elf Ye Xue, defeats Ao Ling of the dragon clan at Tianwu Academy, slaughters the proud talents of various clans in the secret realm, and single-handedly blocks powerful enemies at the Ten Thousand Clans Arena. When the Four Emperors' coalition massively invades the human race, Su Xiao unites with the dragon and elf clans to jointly guard humanity, and fuses the divine powers of all clans to withstand the Pig Emperor. Behind this ten-thousand-year racial melee, an astonishing secret left behind by the Human Supreme is unexpectedly hidden.