Obtained: Speak to the villager at Olive Village in the East Ravine Area during post game as Gohan. If you don’t have it unlocked, try completing his other sub stories first.
Objective: Help the villager find his daughter Ramu
Travel to Olive Village and speak with the villager to learn that his daughter is missing. Agree to look for her then head southeast of the village towards the sub story marker. Interact with the girl there to run into Necke, triggering a cutscene. When it ends, head northeast towards the sub story marker to run into some Saibamen. Defeat them all to complete the story.