Obtained: Speak to Puar outside of Capsule Corporation in West City
Objective: Check on Yamcha
Talk with Puar in West City then head east out of the city. Follow the object to arrive at a highway along the eastern side of the West Area. Approach Yamcha to trigger a cutscene that results in a battle with a couple of Skull Robos. Defeat them to trigger another cutscene completing the story.