In SM008, Samson Oak revealed two Eggs to the students of the Pokémon School. While one Egg was received from his cousin from the Kanto region, the other was found on Mount Lanakila. He decided to give the class an assignment to raise one of the Eggs and offers to let them choose between the two. Mallow suggested that Lillie should choose one of the Eggs and raise it, as it would potentially help her get over her inability to touch Pokémon. Lillie agreed and chose the one from Mount Lanakila, as she preferred it over the other one. She would eventually name the egg Shiron, a name it would retain once it hatched.
After class ended, Lillie and Ash traveled to Lillie's home in order to take care of the Egg. While they traveled, a wild Salandit managed to sneak onto Lillie's limousine in an attempt to attack the Egg. Later, when Lillie was alone in her room, the Salandit revealed itself and attacked the defenseless Egg. Despite her fear of Pokémon, Lillie instinctively shielded the Egg from harm, protecting it long enough for Ash and James to send Salandit flying. After Salandit had ran away, Lillie realized that she had managed to touch the Egg without any trouble, but was still unable to touch regular Pokémon.
In SM013, the Egg hatched into a Alolan Vulpix. In the next episode, Samson Oak assigned the students to raise Shiron, and the students agreed that Lillie should keep it. Lillie caught Shiron despite her fear of Pokémon. On the day of its hatching, Lillie and Shiron spent much of the day bonding while walking in Hau'oli City. They went into a Malasada donut shop, where Lillie had Shiron try some different donuts. When they left the shop, they were challenged by Team Rocket. Shiron defended Lillie, first using Powder Snow to freeze a sidewalk to slow them down, then using Powder Snow to neutralize Mareanie's Sludge Bomb. When a second Sludge Bomb blew Shiron off a rooftop, Lillie jumped off after it and caught it. The two were saved by Ash's Rowlet with Leafage. Shiron then froze Team Rocket with Powder Snow, and they were taken away by Bewear. Lillie had no issue holding Shiron from that point on, though she was still afraid of other Pokémon.