"Jiāsù Zhuìluò" is an original Luo Tianyi song that is featured on Yu Jianliu's album, Zhòng Lì Huàn Xiǎng Qū. It is also the first song of the GRAVITY Series. The song takes place in the future when people could live up to 250 years old due to improved technology and medical care. Since the world was becoming overpopulated, the government carries out "Project GRAVITY": a project where people who reached the age of 20 were brought to a 1,600 meter structure called, "The Tower of the Heavens". Then, they were pushed off the roof unknowingly and fall to their deaths.