Through countless scientific studies, researchers have come to discover the existence of a condensed space known as Sonoro Sphere, within which there is a pure and complete information that remained elusive and intangible. Despite their advanced technology, scientists could not capture or analyze this powerful force, called by scientists Remnant.

The Sonoro Sphere is an important source of information for humans to understand the history and civilization of the Lament because it captures everything that once happened in a specific time and place.

The Sonoro Sphere is an illusion in which the environment within ever-chaning. It made of Remnant frequencies but is often contaminated by impure frequencies as well, the Reverberations. The environment changing is due to the presence of frequencies extraneous to those inside the Sonoro Sphere, which merge together and transform reality. Entering a Sonoro Sphere causes it to mutate, making it difficult for researchers to study its original nature. This is due to the fact that a human subconscious can 'resonate' with such abnormal frequencies.

Baizhi’s ninth Sonoro Sphere expedition revealed a breakthrough.

Thanks to scientific research and technologies developed over time, researchers have succeeded in recreating the Artificial Sonoro Sphere in order to build artificial simulation areas for both military and medical purposes.

The goal of the creation of the Artificial Sonoro Spheres is to extract pure Remnant Energy and to eliminate the abnormal impure frequencies within as much as possible. Unfortunately this is not always possible.

In addition to being formed from pure Remnant energy and impure Reverberation energy, Sonoro Spheres can also be created solely from impure energy. In fact, the events of the story suggest that Phrolova is capable of manipulating Reverberations, converging them all together, and forming true Sonoro Spheres. These areas are also referred to as "Fields of Sound," a concept deeply connected to both the Remnant and its decayed counterpart: the Reverberation.