The future of Earth is hidden on the surface of Mercury. Aki Shiraishi is a high school student working in the astronomy club and one of the few witnesses to an amazing event–someone is building a tower on the planet Mercury. Soon, the enigmatic Builders have constructed a ring around the sun, and the ecology of Earth is threatened by its immense shadow. Aki is inspired to pursue a career in science, and the truth. She must determine the purpose of the ring and the plans of its creators, as the survival of both species–humanity and the alien Builders–hangs in the balance. Aki Shiraishi is a high school student working in the astronomy club and one of the few witnesses to an amazing event–someone is building a tower on the planet Mercury. Soon, the enigmatic Builders have constructed a ring around the sun, and the ecology of Earth is threatened by its immense shadow. Aki is inspired to pursue a career in science, and the truth. She must determine the purpose of the ring and the plans of its creators, as the survival of both species–humanity and the alien Builders–hangs in the balance.