We first meet HyunJin from the perspective of a cat. We hear You and Me Together(?) playing in the background as she sits in a room made of light and her color yellow. This symbolizes the Cosmos. When HeeJin created the three primary colors, yellow, blue, and red she put them into their own dimension of the LOONAVERSE, or the Cosmos. And hearing You and Me Together symbolizes that HyunJin misses HeeJin and wants to get back to her. But how? We know that the LOONAVERSE follows several biblical rules, including that if you sin you must fall from heaven. In this case the Cosmos being heaven. So HyunJin must sin in order to get back to HeeJin, and she can't do it alone.
We hear the sound of something breaking from another room and HyunJin seems startled. She follows the sound to a broken vase, with thistles and water strewn across the floor. This shows us that HyunJin isn't alone, someone has arrived. And as theorized by twinfish, thistles are a symbolism of royalty, which we can associate with Go Won. We are later confirmed that this is in fact Go Won with the Starlight Cinema Theory, and that she has come a long way to meet HyunJin.