Walkthrough: Just north of Iki Town is Mahalo Trail. As you enter with your player, you will see the same mysterious girl that you saw in the Prologue. Mahalo Trail leads to the Ruins of Conflict, and it appears as through that's where she is heading. As you continue to follow her, she will stop just before Plank Bridge as the Pokemon in her bag will jump out and continue down the bridge. As it does, a pack of Spearows will attack it.
Since she isn't a trainer, the girl, who will later introduce herself as Lillie, will ask for you to save the Pokemon called Cosmog, the same Lillie has named Nebby. As you head to save Nebby, you will be attacked by one of the Spearow and forced into battle. By defeating it, your player will quickly shelter Cosmog from the ensuing Spearows. As you do, Nebby will attempt to teleport out of trouble once again, causing for the bridge to collapse and the two of you with fall to your doom. However, before hitting the rocks and water below, you will be saved by none other than Tapu Koko, the Melemele Island Guardian. After it departs, Lillie will give you the Sparking Stone it leaves behinds.
After all of this occurs, you will head back to Iki Town to meet Kahuna Hala, the same who is actually the Grandfather of Hau. He will ask you for the same stone Tapu Koko leaves behind, promising to return it to you shortly.
Items:
Sparkling Stone - From Lillie After Saving Cosmog
Electric Seed - Opposite Side of Plank Bridge