Ayerton Grenavan  

, エアトン・グレナバン

Ayerton initially appears in the series as a scientific officer on board the US warship Abraham, tasked with investigating sea monster sightings. He later encounters Jean and Nadia on a mysterious island where he is partially buried and heavily intoxicated. There, he tells them about a strange witch who lives on the island, which turns out to be Grandis. Ayerton falls in love with her and tries to impress her by pretending to be an English nobleman inheriting wealth from his family. Despite being somewhat eccentric and struggling to distinguish between reality and fantasy, Ayerton is ultimately revealed to have been a wealthy and noble individual who returns to his homeland in the epilogue.