Rozen Maiden (2008)

In the original timeline of Rozen Maiden, shut-in Jun Sakurada chose to wind up the sentient Rozen Maiden doll Shinku and help her participate in the Alice Game, a contest between the dolls. But if Jun had chosen not to wind her up, his life would have been very different.

In an alternate universe, Jun has grown up and is in college, but he is gloomy and still bears the scars of his hikikomori past. While working at a bookstore, he finds a weekly book series called "How to Make a Girl," which includes a spring to wind a doll. When he arrives home that night, the next volume in the series is waiting in his apartment, along with a case for the doll and some parts to make the fifth Rozen Maiden, Shinku. But once he has most of the pieces, the books stop coming, and he receives a letter revealing publication has stopped. The letter also states that to get the rest of the doll parts, he will have to retrieve them from a place called the N-Field.

As if things weren't strange enough already, he begins to receive emails from his younger self, asking for his help in defeating the malicious seventh doll, Kirakishou. So with an incomplete doll, Jun enters the N-Field, unaware of the events that will unfold.