Tengai no Vault

In a world where mysterious objects known as "Managed Items"—capable of triggering phenomena beyond human comprehension—have appeared, humanity lives divided between the "Upper World," home to a massive metropolis, and the "Lower World," a vast, desolate wasteland. Tetsuka, a member of a special unit tasked with collecting these items, carries out missions alone in the Lower World while searching for clues regarding his missing younger sister.