[Machine Translation] The deep underground world was previously thought to be devoid of life. However, a vast number of microorganisms have been discovered in the sedimentary layers of the seafloor. Microorganisms inhabit an extreme geological environment more than 1,000 meters below the seafloor and tens of millions of years old. This section introduces ocean scientific drilling surveys and frontline research that challenge the limits of life and the mysteries of the existence of life.