Heaven's Door is a collection of bizarre and trippy short stories from Keiichi Koike (Ultra Heaven), who I consider to be a very underrated Sci-Fi author.
The last few stories aren't as good as the earlier ones, nevertheless reading this one was a really good experience. Some of the stories also have references to the other stories written by the author.
The artwork and the panel structure was something I liked a lot, with plenty of detailing and cool scene angles.
If you are looking for a short Seinen, Sci-Fi, Psychological series with great art, then I highly recommend this one.