Susy, also called Suzie or Sūjī, is a human whose journey starts after a tragedy. Her father, the chief of Miroku Village, fell ill, and she sought Tenjiku Mushrooms to make his medicine. Her search was cut short when infected Asobots attacked the village. Her father was killed protecting Goku, leaving Susy orphaned.

After her father's death, Susy decides to join the quest led by Sanzo and Goku. She is driven by a desire to see the fulfillment of a prophecy her father often shared, which told of a youth from the Tenjiku Desert and a bandit from Kaka Mountain uniting to save the world from destruction.

On the journey, Susy acts as a moral guide for the group, especially for Goku, frequently scolding him for his recklessness and his pursuit of pretty girls. Though she has no innate fighting skills and is not an Asobot, she shows resourcefulness. She operates a flying vehicle for transport and later obtains a significant weapon: a bow that generates sounds able to influence Asobots. This weapon is unique, and only she can wield it properly.

Her development is characterized by increasing empathy. This is most evident in the final confrontation with the main antagonist, Professor D., also known as Ryutaro Demon. After the group collects all 49 keys, Susy uses her special bow, the Bow of the Sun, to calm the antagonist's soul and grant him peace. This act stems from her distinct ability to comprehend his feelings and motives, revealing profound compassion.

Once the main mission is complete and all Asobots infected with the Destruction Virus are cured, Susy chooses to travel back to the past with Goku and the rest of the group to continue adventuring.