Lee Eun-seol is a school-girl ghost that was killed by a truck. Before her death, Eun-seol had wanted to be Ga-young, Yoo-jin and Joo-hyun's friend. She followed them to Kingdom Mall one day, but after overhearing them mocking her, she ran away and was hit by an oncoming truck. Later, the three tearfully apologize for treating her badly, and Eun-seol shows her forgiveness when a nearby vending machine drops three sodas, in their favorite flavors.
In episode 2, is it shown in a flashback that Eun-seol had frequently tried to become friends with Ga-young, Yoo-jin and Joo-hyun however the girls thought she was a burden. When the girls finally asked her to leave her alone, she feels alone and upsets. She walks outside and is killed by a truck running over her While Park Ji-eun was watching.
Before her death, while getting drinks for the clique she drops her phone and Ji-Eun picks it up. But after noticing how mean the girls where being to Lee Eun-seol she keeps the phone and after her death. With the phone, she sends the three a photo of themselves in front of the mall's fountain with a photoshopped Lee Eun-seol.
The girls decide to investigate Lee Eun-seol death by returning to the place that they took the photo. Unbeknownst to the girls, the real ghost of Lee Eun-seol is watching them.
After the mystery of the photo is cleared up, Ga-young, Yoo-jin and Joo-hyun's tearfully apologize for treating her badly. Eun-seol shows them forgiveness when a nearby vending machine drops three sodas, in their favorite flavors.