Ethanbaron V. Nusjuro features as a key antagonist in the 'Egghead Arc', also referred to as the 'Egghead Incident'. The arc unfolds when the World Government decides to assassinate Dr. Vegapunk upon discovering his forbidden research on the Void Century. The incident escalates on the island of Egghead, where Monkey D. Luffy, a Four Emperor, has taken refuge.