Indian Poker

Indian Poker (インディアンポーカー) is a type of card which allows one to view the dreams of another. Originally created by Kuriba Ryouko, they have been created and spread around Academy City.

Etymology
Indian poker, or, is a poker game where the players see the cards of the other players except their own. Each player is dealt one card which is displayed to the other players, traditionally stuck to the forehead like an Indian feather, followed by betting as to whether they have the highest card based on the other player's cards and their bets.

Production
A dream is recorded on the card by someone who attaches a machine to themselves when they sleep. Then the person who has the card may view the same dream that was recorded on. The instructions for making the machine used to create the card was released by someone online for free. The machine is created by combining various artificial esper power toys. The type of dream input into the card will affect its color, with orange being linked to joy and happiness. To use the card, one must put it on their forehead when they sleep. It is also said that the cards are good for learning by having someone of high proficiency in some subject create a card, for example learning another language or becoming skilled in a sport.

Dream Ranker
Those with the ability to create great dreams for others are known as a Dream Ranker (ドリームランカー). Those that can create useful cards are given ranks, with the highest being "S" or "A" rank, whose cards can sell for lots of money. A similar ranking system is also used for the cards produced.

Transactions
Normally, Indian Poker cards are exchanged between circles of friends without any monetary exchange involved. However, the demand for particular cards increases as the value of the card increases, allowing people to earn an income out of performing transactions involving Indian Poker cards. (One notable exception is the high-ranking Dream Ranker known as BLAU, who distributes his Indian Poker cards for free. ) For this reason, some people act as "traders", who mainly engage in transactions involving Indian Poker cards, notably the exchange of a single card of a particular rank for multiple low-ranked cards or the direct purchase of a card using money.

Background
The Indian Poker cards were created by Kuriba Ryouko after she learnt of her mechanical doppelganger, created as a result of the experiment where she had been separated into two cyborgs for a year before being recombined, which apparently had the effect of creating another soul which came to reside in the combined cyborg parts. Unable to come up with a solution with her own knowledge, Ryouko hoped that by spreading it through the Indian Poker cards, it would eventually mutate to produce a solution or find someone capable of achieving a breakthrough.

Dream Ranker Arc
Misaka Mikoto is introduced to and given an Indian Poker card by the Ringlet curl girl as an attempt to apologize for causing her and Shokuhou Misaki to quarrel. She explains it as a popular card used to peek into the dreams of someone. After receiving the card, Saten Ruiko explains its purpose and how it was made to Mikoto. After using the card that night, Mikoto dreams of a world filled with Gekota which greatly pleases her. She frolics around with the Gekota until she is led by one of them to a castle and meets the queen who turns out to be Misaki. She is then forced to be the maid of Misaki for the remainder of the dream. The sheer rage Mikoto felt during the experience allowed her to forcefully leave the dream.

The following day she meets up with the Ringlet curl girl again and is invited to tea. On arriving she finds Misaki also there, displeasing both of them. The two then overhear Aogami Pierce, going by the Dream Ranker name BLAU, distributing erotic dream cards to various other boys for free. After hearing about cards that involve them, Mikoto and Misaki team up to destroy the cards and erase them from the memories of the boys.

Several days later, Mikoto learns from Ruiko about the ability of Indian Poker cards to help a person in learning a particular skill, which in Ruiko's case is the skillful use of a kendama toy. Although interested about the effects of Indian Poker cards, she remains apprehensive about using it after her experience with the ringlet curl girl's card. Mikoto then encounters a man who set up a makeshift stand for trading and selling Indian Poker cards. Kinuhata Saiai is also present as the card trader's customer, but Mikoto does not seem to recognize her, and Saiai is off-duty and does not want to engage in unnecessary business. Mikoto keeps her sentiments about Indian Poker cards, until the trader shows his only S-rank card in possession, which he identifies as the Bust Upper.

Trivia

 * This concept is similar to the Level Upper in that it was created and spread throughout Academy City, becoming a trend, in order for its creator to resolve a certain problem they are unable to on their own.