Ken Amada is the youngest human member of SEES, and one of the two who don't attend Gekkoukan High School. He is mature, but sometimes he is too precocious for his own good. He uses long spears to make up for his short stature. His Personas can be used for healing, and to cast light-based spells that occasionally instantly kill the enemy. Ken is invited by Ikutsuki to live in the SEES dorm because he is an orphan with no home to return to. He is revealed to have the potential to wield Persona and is asked to join the organization.
Initially, the Main Character and his friends believe that Ken joined SEES out of altruism, but his true intentions are far darker. Ken's mother was accidentally killed by Shinjiro during a SEES mission, and Ken infiltrates SEES in order to kill him.
During Ken's confrontation with Shinjiro, Takaya intervenes and reveals that Ken has been planning to commit suicide after killing Shinjiro. He also reveals that Strega has been supplying Shinjiro with special drugs to control his Persona, and that the drugs will soon kill him. This completely shatters Ken’s hopes of revenge. After a brief fight between Shinjiro and Takaya, the Strega leader takes a shot at Ken. Shinjiro jumps in front of the bullet. Dying, he reminds Ken that he is still a child with a whole life ahead of him and a future that can be about more than vengeance. Shinjiro's last words inspire Ken to fight for the future his mother would have wanted for him.
According to character designer Shigenori Soejima, Ken was designed to have a nostalgic look, rather than to reflect the style of modern Japanese children.