Obtained: Interact with the Saibaman near West City in the West Area during the main story A Shred of Hope
Objective: Defeat all enemies
Travel to West City, then head north near the center of the map to find a Saibaman. Approach it for a small cutscene ending with a battle (if you say yes). Defeat all of the enemies to trigger another cutscene leading to another battle with a Super Saibaman! Defeat it and the next set of Saibaman to complete the story.