Two brothers lose their mother to an incurable disease. With the power of "alchemy", they use taboo knowledge to resurrect her. The process fails, and as a toll for using this type of alchemy, the older brother, Edward Elric loses his left leg while the younger brother, Alphonse Elric loses his entire body. To save his brother, Edward sacrifices his right arm and is able to affix his brother's soul to a suit of armor. With the help of a family friend, Edward receives metal limbs - "automail" - to replace his lost ones. With that, Edward vows to search for the Philosopher's Stone to return the brothers to their original bodies, even if it means becoming a "State Alchemist", one who uses his/her alchemy for the military.
After experiencing a bizarre dream, Madoka Kaname, a kind 14-year-old girl, encounters a magical creature named Kyube. Madoka and her friend Sayaka Miki are offered the opportunity of gaining magical powers if they agree to make a contract with the strange little being. He will also grant them one wish, but in exchange they shall risk their lives by accepting the responsibility of fighting witches. Invisible to human eyes, witches are catalysts of despair in the areas they inhabit. An ally of Kyube, a magical girl named Mami Tomoe, befriends and encourages the two girls to accept the contract. For an unknown reason, another magical girl named Homura Akemi is determined to prevent Madoka from accepting the deal.
Lain Iwakura appears to be an ordinary girl, with almost no experience with computers. Yet the sudden suicide of a schoolmate, and a number of strange occurrences, conspire to pull Lain into the world of the Wired, where she gradually learns that nothing is what it seems to be... not even Lain herself.
Steins;Gate is set in the summer of 2010, approximately one year after the events that took place in Chaos;Head, in Akihabara. Physical locales of Akihabara like the Radio Kaikan building can be spotted in the game. According to Chiyomaru Shikura, who headed the planning of Steins;Gate, Akihabara was chosen because it is an easy place for acquiring hardware parts, which makes it the ideal place for people interested in inventing and tinkering with things. The notion of time and time traveling are the main themes of the game. The concept of cause and effect is featured prominently in the game as the protagonist travels back in time numerous times to perform different actions in an attempt to alter what has happened in the future.
In a world where dead people turn into books and are stored in the Bantorra Library where anyone who reads a book can learn their past. Bantorra Library is maintained by Armed Librarians who wield psychic powers and their enemy is a religious society known as Sindeki Kyōdan.