Dream Ranker Arc

Dream Ranker Arc is a story arc in the Toaru Kagaku no Railgun manga series. The story focuses on a series of events involving a group of people called Dream Rankers and the trend of sharing dreams using a specific kind of technology.

Dream Ranker Technology
A recent trend among the student population of Academy City involves a set of cards called Indian Poker and related technology that allows a person to capture one's dreams and store it in a card-like form for other people to use. The fad manages to seep through the School Garden of Academy City's District 7, allowing one of its students to acquire and share her own dreams with others.

Shared Dreams
During class, Misaka Mikoto and Shokuhou Misaki enter a typical short argument against each other. A third girl involved, who is a third-year member of Misaki's clique, feels responsible for causing the encounter between the two and meets with Mikoto later during the day. Here, as a peace offering, she hands a card to Mikoto. Mikoto does not know anything about the card she received, but her friend Saten Ruiko explains that it is part of a recent trend involving cards used to share dreams with other people. Curious about how the card works, Mikoto uses it that night and ends up in a fairytale land with several Gekota-like characters serving a queen who resembles Shokuhou Misaki herself. In her rage after being dressed as a maid and forced to serve Misaki, she snaps out of her dream.

Although Mikoto loses her interest in learning more about Dream Rankers, she catches wind of more details about them through Ruiko. She is later invited by the Ringlet curl girl to have some tea that afternoon, only to find out that it was the latter's plan to bring the two Level 5s of Tokiwadai closer. The three girls then overhear a conversation nearby involving a Dream Ranker who belongs to the highest rank, known to his patrons as BLAU. Although BLAU claims to share his dreams for free, the sheer amount of indecent content he propagates is enough for Mikoto and Misaki, after hearing that they have both ended up as one of his "targets", the two make a temporary truce in order to deal with him swiftly and destroy any Dream Ranker cards in the possession of BLAU and his companions.

Treasure Hunter App
Elsewhere, in the morning of September 27th, an accident was reported to the authorities. Among those who began an investigation about the event were Judgment's Uiharu Kazari and Shirai Kuroko. Both Kazari and Kuroko were informed about a particular mobile application which allows users to earn prizes by capturing images of designated areas of the city. The app also tags locations of accidents, whether it has happened before or will happen in the future. In addition to this, the app has a prediction window of twenty to forty minutes (ten to twenty minutes off the indicated time) and is known for its high rate of success.

Kuroko suspects that an esper that uses an ability similar to Precognition may be involved with the app and takes Kazari to head to a nearby roadside where an accident is predicted to happen. Just as foreseen, an accident involving a truck and a car occurred at the location. Kuroko, however, manages to save a student that was caught in the path of the accident. After confirming that there are no casualties, Kuroko heads to the nearest building with a vantage point of the area as she suspects that the one who made the predictions will be nearby to confirm them. There, she meets a boy with the appearance of an elementary school student, who quickly introduces himself as the creator of the Treasure Hunter App.