Yuumei Sakai o Koto ni Suru

On a usual school day main character has lunch with his senpai at the old school building library. He finds a pre-war period letter indicating a place where something important is hidden. Under an old tree there is a box with cards and instructions. The two students get trapped in another dimension with the only way out being to follow the instructions. [From [url=https://vndbreview.blogspot.com/2019/08/vn-of-month-september-2004-abandoner.html]vndbreview[/url]]