Aboard the Janus, a ship carrying twelve young survivors across hostile space, normalcy shatters without warning. As the vessel charts its course toward Taut, crew members vanish one by one, leaving behind only confusion and fear. The remaining children must confront a mystery that defies explanation: where have their companions gone, and what force pulled them away? Paranoia creeps through the ship's corridors as theories multiply faster than answers. Some suspect sabotage from within. Others fear something lurking in the vastness beyond their hull. With supplies running low and trust fracturing, the young crew faces an impossible choice: continue forward blindly or risk everything searching for the lost twelve. This OVA strips away the comfort of the main series' steady narrative rhythm, replacing it with tension and uncertainty. The tone shifts from adventure to thriller as claustrophobia sets in and the line between ally and threat blurs. For viewers who thrive on mystery and want to see how these young survivors handle genuine crisis, this sidestory cuts to the heart of what happens when hope meets real danger.