In the near future, there is a super city called "Candle Dragon City". Technology is highly developed, and brain-computer interfaces, AR reality enhancement, and consciousness uploading technology (submersible technology) are popular. However, the gap between the rich and the poor in society is wide open, and giant companies monopolize everything. The story revolves around a mysterious organization called "Echo" who use a dangerous technology to explore the "abyssal sea" of mankind's collective subconscious in an attempt to uncover the hidden truth.
