To battle the alarming suicide rate, the government initiates a suicide prevention program using AI robots. CHA-88K, a humanoid robot, is placed on Mapo Bridge, the nation's highest suicide spot. "Cha Cha" receives a lot of attention in the beginning, but is eventually considered a failure and funding for the programs stops. However, Cha Cha continues to watch over the bridge. Due to her ability to infinitely synchronize with other AI robots, she can observe the private lives of many humans. Cha Cha despairs over what she sees in human society and develops something similar to depression and lethargy. Ai, CEO of White Island Nursing Home, purchases the decrepit Cha Cha from the government, brings her to the nursing home, shakes her out of her stupor, and ultimately convinces her to become Earth's next "Mother." In a futuristic society where people have become cold and calculating machines and AI robots take over many services once performed by human beings, Cha Cha, Ai, and the other AI robots force us to examine what it means to be human. (Source: NHN comico Corp.)