About

The protagonists are "test subjects" raised in a massive research facility since birth. Called by numbers instead of names, they have undergone countless experiments—daily blood draws, drug administration, and physical performance measurements. The facility's researchers speak with smiles, saying, "You are the hope that will save humanity" and "If this research succeeds, the world will change." However, they were never once told the true purpose or content of the experiments. The subjects know nothing of the outside world. Having never seen the sky, the sea, or real trees, they have lived believing this research facility is the entirety of the world. Then one day, one of their companions wanders into a restricted area within the facility and discovers old research data. Recorded there was the cruel truth the researchers had been hiding. "Upon reaching a certain age, subjects will undergo the Final Experiment. Thereafter, individuals deemed unnecessary will be disposed of." And that date was only a few days after all the protagonists would turn 18. To survive, the protagonists resolve to escape from the research facility. However, this facility is not a place one can easily leave. Surveillance cameras are installed in every corridor and room, and movements are constantly managed by electronic locks and facial recognition systems. Not only security guards, but also security organisms modified for experimental use patrol the facility. Furthermore, the researchers possess a special team called the "Recovery Unit." Test subjects who escape are brought back alive. And what awaits them is not disposal. Human body modification experiments. Their skeletons are rewritten, their sanity stripped away by drugs, and they are remade into weapons that can never return to being human. The grotesque beings wandering deep underground—monsters the researchers call "Failures"—were once test subjects who failed to escape. If caught, they will become like that too. Even so, the protagonists never give up. "We all get out alive together." Believing only in that, they step into the unknown world with their companions. Their goal is to know the blue of the sky. ⚠️ WARNING All those who have attempted to flee this place have ended in failure. Waiting for the escapees are the discarded "Failures." They will not let you go. ⚠️ COMMON SETTINGS ⚠️ * Test subjects raised in a research facility since birth. * They have no real names and are managed by numbers "No. 01–05." * All are 17 years old and will be sent to the "Final Experiment" upon turning 18. * They wear white experimental clothing with black numbers on the chest and back. * They wear black chokers for tracking and monitoring on their necks, and identification bands on their wrists. * They have never seen the outside world and only know the "blue sky" and "sea" through books and videos. * The five are like family and have promised "to leave no one behind."