Nept is a humanoid demon serving the Zoble Empire as a naval admiral. He presents a rugged, one-eyed military officer appearance, consistently wearing an eyepatch. Displaying relatively sound judgment and strategic thinking compared to his typically eccentric demon peers, Nept possesses the combat ability to transform his entire body into monstrous forms. However, this transformation offers limited tactical advantage in actual confrontations. Assigned to an assassination squad targeting the Idaten deities, Nept engages Prontea in battle and is defeated. Following his defeat, he is captured and subjected to neural reconstruction procedures conducted by the deity Ysley for research and intelligence gathering.