|Spoiler warning: Plot or ending details follow.|
Nexus (green door) → Forest → Go north till you reach the first section, then go to the section on the east. Interact there with a red flower.
Nexus (blue door) → Snow world → Enter the igloo with two snowmen standing from the both sides of it and interact with the snowman inside it. (See a screenshot of the igloo.) (Entering any other igloo will warp you back to the entrance door to this area.)
Nexus (dark grey door) → School → go down the three halls till the end, interact with the light in the end. You will reach a room with a scenery. Cross the room and interact with the purple flower.
From the nexus go through the green door to the forest. From the section you start at, go. You will know it's the correct he correct section when you will see a little colourful sign. (see screenshot) Interact with and you will reach the Prairie; find there a pair of symmetrical trees and walk between them. In the next location, climb the ladder to the sky then interact with white flower.
From the nexus go through the green door to the forest. From the section you start at go north for 2 sections, then go west for another 2. You will know it's the correct he correct section when you will see a little brown sign. You may try to interact with it to get a short dialogue, but unless you can read Japanese, it will not help you much.
What it actually says is something like: "From me, take 2 steps downwards, then 4 steps to the right". Follow these directions and press "interact" when standing on that square. If you fail to find the right square, see the attached screenshot where Baratsuki (the heroine) is standing on the square you need to interact with while stepping on it.
If successful, you should be teleported to a different location - a yellow sand-like road. Go up that road then interact with the person under the tree who looks like Baratsuki.
The sign says:
Examining from the front
(Take) 2 steps down (then) 4 steps to the right
Fangames Reference RoomEdit
Nexus (dark grey door) → School → In the 2nd hall, enter the open classroom, interact with the big red eye on the wall → White Room (go right and interact with the edge) → White Desert. Go between the two pairs of figures that look like people and you will reach the fangames reference room.