The story tells about Kelvin, a summoner who traded his memories with the goddess and was reincarnated from another world. Although he lost all his memories, he has the strongest skill combination in history and a passionate spirit of "fighting". As the lowest-level adventurer, he bravely challenges impossible tasks and the strongest opponents in order to level up. Not only did he make a contract with the reincarnated goddess, he also conquered monsters such as the gluttonous slime and the black spirit knight one by one, and led these subordinates on an exciting and magical adventure.