The stage is set at Nekomi Institute of Technology and its surrounding areas, located in Nekomi City, Chiba Prefecture. Additionally, the place name "Nekomi" actually exists in Nekozane, Urayasu City, Chiba Prefecture. The story begins when the protagonist (at the start of the serialization), Nekomi Institute of Technology student Keiichi Morisato, mistakenly calls the "Goddess Help Line" (though Keiichi believes he dialed the wrong number, it was actually the World Tree's function operating to bring about his salvation). Startled by realizing his mistake, Keiichi hears the words "I'll be right there" from the phone, and then a goddess named Belldandy appears in the mirror. Belldandy asks Keiichi what his wish is, to which he replies, "I wish a goddess like you could stay by my side forever." This wish is granted by the heavenly realm. From then on, Keiichi and Belldandy begin living together.