If you're looking for anime similar to Alien Nine, you might like these titles. All recommendations are made by Anime-Planet users like you!
"I have only abandoned my body, I still live here" - are the words emailed to friends of Chisa, several days after her death by suicide. As Lain delves deeper into the world of the "Wired" (also known as the internet), the line between it and reality becomes more and more unclear. Close the world, open the nExt.
Both Lain and Alien Nine are scary, quirky, and off-beat. Both series are also brief but well-executed story-telling gets the point across. (Alien Nine doesn't have a definitive ending.) Both stories center around a timid girl put in bizarre situations, and nobody else seems to notice.
Also, if you really appreciate clever soundtracks then you should watch both of these series. They're total opposites but they're very effective. Lain sounds like electric buzzing, city sounds, and techno; Alien Nine sounds like a magical girl show with happy J-Pop despite the horror on-screen.