Main Walkthrough

Location: Great Sandy Desert
Petitioner: Saien the Scientist
Reward: Eye-lashes's Record Cube, Saien's Necklace, 30,000 Berries
Objective Reward: Roast Chestnut Ball

To trigger this quest you need to make your way to the Great Sandy Desert, located to the north of the Ravine of No Escape. Once you're in the desert for the first time you'll run into Desert Bandits, and to continue the main quest you'll need to head to the northeastern 'corner' of the southern half of the Great Sandy Desert. While you're up here you'll find the petitioner, Saien, sitting on a nearby rock.

Saien is experimenting with the animals of the desert, trying to tame especially dangerous ones so they're harmless to people. He was successful with a Sandora - but it ran off in pursuit of a camel with some very nice eye-lashes. Saien suggests checking out the Sandy Ruins to find the pair.

You won't catch up with Eye-lashes until you've crossed through the Sandy Ruins and completed several story beats. Once you're in Great Sandy Dunes, at the bottom of a series of ramps out of Sandy Ruins, head east. There's a rough, half-buried stone road that will guide your way. 

Eventually you'll spot a group of bandits standing around a camel with lovely eyelashes, and, sure enough, it's Eye-lashes. The five Thieves trying to make off with the camel aren't going to let him go without a fight, so you'll need to take them on. Most of your opponents are Technique types, making Nami and Usopp good choices for your team, though there's also a Speed and a Power type mixed in. Paralysis Bag will prove an annoying Skill unless you take the Thieves out quickly.

Eye-lashes will be grateful... in his own way... for the rescue, and the team will discover that the Sandora Dragon chasing the camel is already gone. For... reasons. You need to report this to Saien, back in Great Sandy Desert, in the same spot where you first met him. There are two ways to get there:
  • Trek back through the Sandy Ruins. This will take a little while, but if you want immediate results it's one way of solving the problem.
  • Keep following the main quest markers until they take you to the oasis in the north of Great Sandy Dunes. This will trigger a little side story that will unlock Yoisa Travel, allowing you to warp to a spot in the south of Great Sandy Desert, near the exit to the Ravine of No Return. You can travel northeast from here to find Saien.
Either way, Saien isn't at all upset over how things went, and he'll give you a reward for your trouble.