For her debut song "Timeless", Zhang released two music videos with a single storyline. The music videos feature Super Junior members Han Geng and Siwon, as well as Lee Yeonhee. The music videos featured a hostage situation, in which the thief (played by Siwon) holds Lee Yeonhee captive. As the police arrive on the scene, a police officer (Han Geng) attempts to negotiate with Siwon. Siwon shows the hostage and points the gun at her. Han Geng pulls out his gun upon seeing her. Another police officer attempts to kill Siwon, but misses, resulting in Siwon shooting Han Geng. As Siwon makes an escape, he pulls Yeonhee's necklace with him, but he puts it away, uninterested. The story then jumps to a year later, where Han Geng is taken off life support. He is listed as an organ donor. At the same time, Siwon suffers a heart attack. He is given Han Geng's heart and survives. Whilst recovering, Siwon experiences flashbacks of Han Geng and Yeonhee, revealing to the viewers that Han Geng was Yeonhee's boyfriend; however, this confuses Siwon. He recognizes a store from his flashbacks and approaches it, seeing Yeonhee inside. Yeonhee helps him to sit while he experiences some heart pains. While Siwon wonders whether they've met before, he notices a picture of Han Geng and Yeonhee. He then makes the realization that he killed Yeonhee's boyfriend. He then goes through hospital documents and sees that Han Geng donated his heart to him, causing Siwon to realize why he's been getting flashbacks. He goes through his stuff to find Yeonhee's locket, showing a picture of Han Geng and her, after which he breaks down. He then goes to return the necklace. The story ends with Siwon begging for forgiveness on his knees while Yeonhee cries, clutching the necklace.
The actors received high critical praise for their performances. The story was broken down into two main parts. The first part focuses on Siwon's recovery after the surgery, and his realization that he killed Han Geng and has his heart. The second part shows the hostage situation more clearly. Zhang and Xiah are featured in the second part of the music video.
The second music video released was for her second track "Y (Why...)" on her debut single. This song is a remake of Jamelle Fraley's song 'Powerless'. This MV features only her, with straight hair and showcasing a more youthful image than in "Timeless". A second version of this music video features a documentary of her training and backstage scenes of the Timeless promotional activities along with Xiah. Zhang has received a well response from fans as the MV shows her working hard to achieve her dream. This music video also shows clips of her playing the violin and her dancing skills.