Natsuzaki no Maboroshi

A flying object suddenly crosses the sky of a small town and falls down in the forest.
Main character leaves the house and starts to live in the forest.
Female childhood friend who had not been in contact for four years, shows up and suggests to reunite as friends.
After a while a mysterious girl comes out of the forest depth and becomes a close friend.
As days change color, reality starts to erode with mysterious events...

[From vndbreview]