Amakusa is a hot-blooded and open young man who cannot stand boredom and is hired by Okonogi as Ange's bodyguard.

He stands by Ange's side despite being originally hired by Eva, who grew to resent Ange. Due to his talkative nature, Eva fired him before her death.

He is skilled at operating many weapons. The events of Dawn of the Golden Witch suggest his loyalties lie more with Okonogi than with Ange.