Sierra no Bouken, Hametsu no Doukutsu

A story where there is no rescue. A rookie scout from the adventurer's guild goes on her first solo adventure and accidentally triggers an out-of-the-way trap in the beginner dungeon. After falling through a trap hole, she finds herself in an unreported labyrinth filled with corpses bearing a variety of mysterious wounds. There is no sign of any adventurer having ever escaped, yet our heroine seeks a way out.