Oshiire no Naka no Dungeon Craft: Koufukude Fukoude Koufukuna Kyoudai

I, Toru Shiina, a high school boy, found that a dungeon portal has been created in a my dorm room closet. Inside, the dungeon is as vast as a video game, and when I reached the bottom, under a large tree in the heart of the dungeon, my eyes widened in surprise. Because my younger sister, A-chan, who