Kyouryuu no Kaitakata

A group of individuals discovers a mysterious key that unlocks hidden doors leading to unknown locations. Each time the key is used, it transports them to a different place filled with strange occurrences and challenges. As they explore these new environments, they must work together to uncover the purpose of the key and the reason behind their sudden appearances in these places. The key seems to have a will of its own, choosing where to take them and when. Some of the locations are familiar, while others are completely alien. The group faces various obstacles and must rely on their wits and cooperation to survive. The story includes an additional chapter that provides further insight into one of the locations they visit.