The Sky Garden is a place accessible by climbing the Stairway to the Sky found in The Wilderness B. As you ascend the stairs, the sky changes from a deep blue-green to a brighter green and you may observe a person falling in the distance. The garden itself is a small area that looks similar to a neatly kept park with lots of trees, benches and lights. A serene music is playing, making this a calming area in comparison to the rest of the game.
If you use the Knife Effect on the Organoid here (the blue alien-like creature shown in the picture at the right), it'll drop 100 yen. But that could be hard as it instantly warps away whenever Madotsuki touches it.
Past the Organoid is a cliff where there are three Maussan Bros staring off into the distance, possibly looking at the UFOs that fly around over a distant city. The building here, known as the Crossover Garden, is a tunnel which has a patch of white lilies at the end of it. Interacting with the lilies an odd number of times and walking back through the door leads Madotsuki into the Ghost World where the Triangle Kerchief effect can be obtained. Interacting with the lilies an even number of times and walking through the door again will lead her back into the Sky Garden.